Bill's unqualified comments

"and now for something entirely different"

2011-10-09T01:53:00.000-07:00

In my last positings I neglected - forgot - to mention that I sold both remaining veterans, the 1954 BSA A7 unrestored and licensed and the 1955 Mondial , also licensed and running - quite well as I was able to log up a couple of hundred Kms before parting with it this year. It has gone to a (hopefully) better home.

That does not mean that I have lost interest in two-wheelers. Not in the least.
I have renewed my very old interest in bicycles and bike riding, though to be truthful, that was never actually completely dormant.
But as one gets older, it becomes increasingly evident, that one is responsible for one's own well-being. Now at 67 I decided that some more time spent actively with the bike was worthwhile. This means of course, unless one has unlimited free time, that other things like motorcycle riding or restoring one's own material have to be curtailed.

My courtyard looks like a bike store. Five racing bike of various flavors hang from their wheels at the front corner, behind that with the basket on the bars, our everyday but nevertheless custom-built "Lea" mixte of 1974. Farther back in the other shot another Lea mixte, this one from 1986 with derailleur and not all Campagnolo. Not seen, a Marin hard-tail mountain bike and a Specialized racing BMX from the early day of real BMX racing. This one lives as a collector's item on the upstairs wall; the little kids are not allowed to use it.

Les Cycles Lea was founded in 1893 in Bruges and was disolved only recently because there was no one left to run the business.

I discovered Eric Prooft , the owner of LEA, during my first visit to the Festival van Flaanderen in 1974. This music festival with playing competition for harpsichord and later fortepiano with exhibition wis carried out every three years. !974, my wife and I were only tourists and, having discovered this fantastic 19th.c. store with real-life master bike maker, I had the first Lea made for my wife. Eric made the frame for these in batches to standard size and geometry as a typical bruggsche fiets, that is a Bruges bicycle. traditionally these differ from say an Antwerpsche fiets. This is due to the very different topography of the two cities and the street surfaces: Bruges mostly cobble stones, Antwerp mostly brick. As long as bike were made in smaller shops by artisans, such differences were catered to. The differences are both visible and obvious for the rider. French mites are different again. Unfortunately most all of this has died out with the artidan makers and the influx of cheap (in every respect) mountain bikes. Anyway, with the idea of getting a bike, we went to the historic shop just a few yards down the street from the gothic town hall and requested such. Between Eric's rudimentary English and my rudimentary French managed to convince him that we really wanted one of his bikes. From then the stock pile on the counter grew. What color, please; the frames were hanging high under the ceiling in metallic red, green or blue. He could do other colors but we would have to wait either until the new batch was finished or he would have to strip one a repaint it. He had his own enamel baking oven at the back, this, too, historic. We chose green. Good, the frame and a fork to match were laid on the counter. How should the wheels be? How much may they cost? What do you recommend? Fine; the hubs, rims and spokes were also laid on the table. Cranks and chainwheel? Fenders? Brakes? Saddle? I really highly recommend this one; it is very dear but will last for decades. OK (and it, a real leather woman's saddle, is still in everyday use!). Bars and Stem? etc etc. at the end a large stock pile covering the counter, all tallied up in pencil one the shop slip. Fine. 'Now you come back at the end of the week and I will have it ready to be adjusted and ridden.' So we came back on Friday and new bike home. It was not cheap. It has Campagnolo Record high flange hubs spoked with Mavic rims for tubulars, Campagnolo pedals, Stronglight D49 cotterless dural cranks and TA chainwheel, Mafac Racer center-pull brakes. A bike like that cannot be cheap. It is still going strong, so at the bottom line it was dirt cheap and it is still much lighter than other everyday bikes and lighter than a lot of would be racers. It has no shift at all; in Bruges you don't need one.

1977 and 1978 we bought each a 24" and 22" Lea mixte for the two daughters. These have been passed on in the meantime.

1982 while passing through Bruges from England - the ferries were still running from Zeebrugge and Ostende to Dover - I dropped in on Eric and had him take measure for a new road racing frame built to his best specifications for the flemish one day classics. The following year, I would be back to the Festival with my harpsichords and we would then finish the bike. All Reynolds 531 double-butted tubing with Campagnolo dropouts, this one got real baked-on enamel. Eric was only to glad for this since he did not like the metallic lacquers at all and only did them because they sold better. Wheels were again Campi high flange Record with Mavic GP4, 28 spokes in front, 36 at the rear with a then revolutionary 6 speed freewheel. Campi cranks and chainwheels, Campi derailleurs, Modolo Speedy brakes ( a small but high quality Italian company), Campi seat post, TTT bars and neck, Campi pedals. Some things have been changed since then. There is now a TA triple chainwheel crank set, a newer more modern Specialized saddle, Miche 302 click pedals and a Dura-Ace rearwheel with 7 speed freewheel. While this is a modern hub-integrated freewheel, unlike the screw-ons used on those historic Campi hubs, cogs for it are no longer available; Shimano changed the spline. Too bad, since the hub is really every bit as good as the Campis. I am making a new rear wheel with Miche B-Box hub with Campi splined drum laced into a brand-new(!) 32 spoke Mavic Monthlery rim which I chanced onto.

I finally found a rather rare Campi rear derailleur (Ebay France like that TA crank set) with long cage arm to manage wide ratio setups so the new wheel will have a 9 speed cluster.

Behind my two bikes in the second photo, there are two bikes with very small frames for the grandchildren. A Bianchi with aluminum frame, carbon fiber fork, and relatively modern Schimano 501 group. It is also the only bike with clincher tires. I bought this one used. Next to that and barely visible, an 80ies Pinarello "Treviso" road frame I built up as fixie so they are forced to learn an even, round cadence.

In the first photo, a japanese Koga Myata I bought for my wife many years ago, but which she does not ride, preferring the younger of the two Leas with derailleur. Altho a bit small, I will put fenders, lights, and Mafac brakes on it this week for myself to use in the winter.

Saving the best for last, This is the bike I ride most.

Made to measure for me in 1962 by Oscar Wastyn Sr. in Chicago, this is one of those professional 6 days bikes referred to on their homepage. Typical of the time, all Reynolds 531, with Nervex Pro lugs, and Campi dropout ends on the fork. I restored it a few years ago to nearly original condition, adding the single brake for everyday use but have since removed it again. Since I started training again, my condition has imporved to the point that I no longer think I need it. The Miche 502 clip pedals are of course not original; I used Campis, but the rest is still as it was, including the then high-tech Unica Nitor Mod.50 saddle: Campi Record high flange hubs, Gran Sport seat post, and pedals (originally), Mavic rims. Stronglicht bottom bracket and 49 cranks (Two sets with 165 and 170mm) and TA chainwheels, Ambrosio stem and track bars.

At the moment I am using campi Super Record road cranks with a 42t ring because I am unable to get new TA chainwheels. I will have a couple made this winter and put the Stronglight cranks back on.

As I said, this is the bike I ride most. If you have not ridden a fixed gear, preferably a real track bike, you don't know what a bike really is. After that you are spoiled. Even the best pro road bike is a clumsy makeshift by comparison.

While I have no need or desire for a modern road bike, I do test ride everything I can get my hands on, regardless of whether I could afford it or not. No aluminum bike has ever impressed me and few are that much lighter than my Lea and only very few carbon fiber bikes. Even the ones that did impress me I would not trade for my Lea. It weighs all of 9kgs with the vintage parts. With modern material like radial spoked carbon fiber rims and a carbon fiber group it could easily be reduced to about 7. With the Reynolds 531 steel frame.

more news

2011-10-08T04:52:00.001-07:00

This year I decided I did not need (who does?!) two so similar rides as my Skorpion XP and my Yamaha SZR. I decided to sell the Yamaha. Not so easy as I found out. Or rather easy enuf, if the price is next to nothing. This was not an option, however.

My SZR is the second oldest one recorded in the owners list in Germany, Nº.132; the first 100 units were not exported out of Italy at all. International sales began with 101.

Since getting it, I have little by little tried to refine it and remove as much weight as possible without resorting to a hacksaw and angle grinder. One of the first moves was to replace the impossibly clumsy clipons with Gilles GP Lights like I was using on all my MZs. A Brembo adjustable blake lever was fit.

New solid pegs as replacements for the utterly impossible fold-up junk were made up using third party so-called racing pegs (so-called because such pegs are not legal in actual racing) and adapters I turned from stainless. The lower one for the right side, turned down for the brake lever. The left side without, since I use a reversed shift lever, first gear up.

Prisms for a ra ing paddock stand were fit using pop rivet-nuts.

A new CNC milled chain wheel with 43t was gotten from Sieg and installed with DID 520ERT2 chain.

Bridgestone BT090 in 120/70 and 140/70 were fit.

By and by, nearly all bolts and nuts were replaced by either aluminum or titanium from Poggipolini. Both brake lines were replaced with steel braided lines from ABM, again with aluminum banjo bolts.

The front rotor was replaced with a Brembo Racing cast iron unit, together with Carbone Lorraine C55 sintered racing pads. Of course, the rotor is bolted on with Ti bolts, the caliper bolted on and also bolted together with Ti bolts as is the rear unit as well. Thankfully, the Yamaha (made in Italy by Belgarda SPA) has Brembo calipers to begin with.

The passenger pegs and their brackets were removed, the bike registered as a single seater. Those things are actually 14mm solid steel and really heavy. I found a CNC milled quick release fuel cap by TWM that fit the OEM (from Acerbis) tank out of the box. I hate those locked gas caps, especially when the ignition key has to be used. I guess this is a leftover from the racing days; race bikes don't usually have ignition keys.

With some convincing, I was able to get Glaeser to make and offer a bubble wind screen for the SZR.

After more coaxing and convincing, I was able to get a Termignoni cup exhaust, never mounted,much less used, from Heinz Weber who had bought it with the idea in mind of reworking it for his very special 14" Skorpion side car bike. Something he thankfully never got around to. When the SZR was introduced, a cup challenge was also started in Italy for which Termignoni made these exhausts which are very well made and light. Now that they are no longer made, they are very scarce and coveted.

With that mounted, I got a high-end can from SR-Racing, made for the XT660R. The can is big but it is also very quiet even though it does not have a DB eater inside. Well thought out and executed as one is to expect from SR.

The next step was to modify the cooling system. the the thermostat housing, filler, and some hoses were gotten off eBay from a YF600.

A T-junction, and hose clamps from a local supplier and a length of garden hose as well.

Unlike the SZR, grown-up Yamahas had a car-like two-circuit cooling system with a true thermostat which is shut when cold, routing the coolant back to the engine without going through the radiator. The "new" thermostat was placed in the center, the feed hose from the water pump to the engine cut apart and spliced with that T-junction so that the coolant from the thermostat, when closed, returns directly thru that garden hose to the water pump. You can see that both the return line from the cylinder head and the garden hose are both at the bottom of the housing below the thermostat valve. Only when it is hot enough, is the coolant allowed out the top of the housing to the radiator. The thermo-feeler for the thermometer is also in this housing so the reading is that of the coolant as it returns from the cylinder head. The modification is easily done, the parts cheap and it is well worth it. The engine now reaches 80ºC. with a few minutes and holds that constant. The original setup almost never exceed 60º except on hot summer days at traffic lights. 60º is too cold. Of course it is easy to block off part of the radiator and many do this to increase the operating temperature.

I left the engine untampered with - or rather I did only those things that required removing the side covers: I fit my lightened flywheel/freewheel assembly and of course I fit that solid balancer gear before something bad happened. The engine itself has never been opened as far as I know. there is no tuning save the lightened flywheel assembly and the exhaust.

I fit a SilentHektik Motocoil with BERU PowerCable as I am wont to do with all my stuff. Of course, I also installed the (for me) requisite Ignitech Sparker TCIP4 set to a maximum spark advance of 29º and the limiter set to 9500RPM. Since finding out about Ignitech three years ago or so, I have sold at least 100 of these boxes all over the world. they are definitely worth it.

The big advantage is being able to set the curve so that one is rid of the chain lash etc. The engine runs smoother, in particular at the bottom end, but I revv this one regularly to 8500 in the lower gears and run it at a constant 7000-7500 in 5th on the Autobahn for 100 km at a time. Despite the stock engine, this bike, reduced from nearly 190kg to 167, is fast for what it is. It takes some nerve and more than a little tuning to be able get away from me. On the back roads, I seldom get out of 3rd, rarely into 4th, never into 5th. keeping the revvs between 6500 and 8500.

After loosing a nut on the rear axle despite using a torque wrench, I decided to revert to the old-fashioned style using a cotter key to secure the slotted nut, the pin itself secured with a length of braided stainless.

This is the state of the bike I wanted to sell. It must be obvious that I cannot sell this for going el cheapo rate. I offered for less with the original exhaust as well. In neither case was there any interest, at least no one inquired although I know that SZRs a constantly sought after.

I resigned myself to retiring the MZ to the attic for the time being. THe MZ is not for sale; it is a one-off bike.

Thus reconciled, I decided it was time to go for Gilles rearsets on this one, too. As mentioned above, the left side had been fixed with a makeshift. this would not do for the Gilles, so I made new part to be welded to the frame and took the bike up to my friend's metal fabricating company. Rolf is an artist with the TIG welder. Nevertheless, he had requested I wait until he had gotten his new AC/DC welder. Since most of his work is done with stainless, he normally needs only an AC welder, of which he has several. His large "Linde" AC/DC unit did not work to his satisfaction with DC, however, and he had ordered an array of new welders to the shop to try out. Then he called me up. We lifted the bike up with the crane onto the welding table (as we had with the other bike for the new exhaust), unhooked the battery, etc, and Rolf welded the new part on so that only someone really in the know can detect it. I lucked out in finding the exact same color in a spray can and the repair was finished, like new - better than new.

Gilles supplied me with 15mm sheet 6061 and I made up the two very different mounting brackets myself, the old-fashioned way, marking out by hand with scribe and square and centerpunch, drilling the holes and tapping. Only then did I cut out the outline at the bandsaw and finish with various files. then the two plates were milled to thickness from behind, there being a 3mm difference between top and bottom mounting points and Gilles' standard thickness being 10mm at the bolting pattern. Done, the brackets went to Gilles to be anodized. the standard parts were picked from the stock list as necessary and - voilá - my AS31GT4SU rearsets were finished. I am satisfied and Gilles is, too, that they look like they had been factory made. In drawing up, I had tried to keep to the Gilles style. As nice as they are, there will be no AS31GT4SU offered by Gilles. The two very different brackets are much too expensive for such a limited market.

I can supply the drawing and the parts if someone wants to make the brackets on his own. One person, admittedly a real SZR "nut", is doing just that at the moment.

And finally, I was fed up with undependable blinker relays and ones that might work at idle but not at speed. I got myself a "m-flash" digital relay from Motogadget and am rid if those problems.

update; news

2011-10-08T02:26:00.000-07:00

Almost a year since I reported anything here; not a whole lot to report. Since my last writing, I have built a couple of engines, both 3YF and SRX.

Last fall, about this time, I did some mild tuning(101mm flat top WISECO, Megacycle 280/2 and Kibblewhites, porting; solid balancer gear, the usual) on a SZR which included modifying the airbox to accept a TM34-B65. Using a standard flexible idle adjuster similar to the one standard to the SZR, I routed the idle through the airbox and out through the left side where it can be reached by a long Phillips screwdriver. Normally, with both the SZR and the Skorpion the idle adjuster is inaccesible as long as the the seat and in the case of the SZR the tank are in place.
I made a one-off exhaust system for it. Using header for the XT660R gotten off eBay, The OEM XT 660 headers are 32mm ID instead of31,5 OD like the original SZR, thus nearly the same as the Termignoni headers that were once available (and which I use myself) I rebent those around the oiltank and made a Y-junction under the engine leding into a larger connecting bend to the Rombo can the owner already had. All joints are slipon.
I also modified the cooling system using YF600 parts (thermostat housing and filler) to be a true two-circuit temperature controlled system, unlike the original (and that of the Skorpion as well) in which the thermostat only reduces the cross-section slightly. Through the modification the engine reaches operating temperature quickly and remains at an almost constant 80º. The original system never reaches a good operating temperature at all except in summer city traffic. It is probably alright in Rome...
Otherwise, the torturing OEM clipons were replaced with PT which I had in my racing kit.
I also built up an engine for a heavily customized Skorpion using a bottom end from me. It has a SZR cluster with shorter 5th gear, solid balance gear, roller chain conversion, roller crank bearing on the right, much lightened balance shaft, lightened cfankshaft with Carillo. The cyclinder got a 101 flattop WISECO, the head was ported, a Megacycle 280/2 an Kibblewhites were already installed. A TM36-B70 is mounted with an oval K&N, there is no airbox. The owner had made up his 2-2 exhaust system utilizing two Akropovic cans.

The owner had also converted the frame to "oil-in-frame" - you can see the return oil line in the photo - and also made a very spartan seatframe. He had fit a tank from a Cagiva MITO to which he laminated a glass racing seat from the classic scene, the whole of this hinged at the front; you can just barely make out the black steel hinge bolted behind the head.

The seat frame carries the entire electric under that seat cowl on two levels. I made the entire wiring loom for this bike, utilizing a SilentHektik electronic fuse box , a 4,5Ah LiFePo battery, an Ignitech Charger rectifier, and an Ignitech Sparker ignition.

Fuse box and ignition are on the top level. The black capped connector hanging down across the blinker in the photo is for the battery charger so the nothing need be removed or opened to charge the battery.

Beneath that, the battery, with its separate connection posts. Everything is connected to the two posts, not directly to the battery which can be removed without disturbing anything else. Next the the posts is the starter solenoid with the shortest possible heavy plus cable from the post and leading straight to the starter. Likewise, the heavy minus lead to the starter is separate from the rest of the harness. Two further 2,5mm2 ground wires (blue) ground the seatframe and the the fork with switches and headlight. the separate fuse older is in that charging lead.

The key lock and ignition switch was mounted on a new, welded-on bracket on the frame on the right side. In front of that, you see the oil temperature pickup fitted to the frame. The ignition switch turns on +12v from the battery to the SilentHektik fuse box and nothing more. That box has 3 8A automatic fuses, the blinker relay and a relay as well. that relay switches +12v for both the ignition box and coil on when grounded by the kill switch. The fuses are for 1) the front end, 2) the tail end and 3) extraneous stuff like the horn. The blowers and thermoswitches have their own inline fuse completely separate from the ignition key. Basically, this entire setup is as I have it in my own Skorpion and ha on my blue bike as well, both with the SilentHektik fuse box. A Silenthektik Motocoil is used together with a BERU PowerCable R118-060.

Personally, I prefer the BERU Ultra spark plug as well. I use a 12-5DU.

This is the finished bike. I was not able to test ride this one so I could not weigh it at the farmer's coop.

over two years ago, I reported on the Gilles rearsets I put together for the Skorpion. Gilles agreed to offer these officially for the Skorpion as AS31GTMZ01. Several sets have been sold including two sets to England.

Apart from these two, I built up another two XTZ engines and an SRX engine as well as redoing a Ducati M900. Don't ask!!!!

Swapping clusters

2010-12-29T09:26:00.000-08:00

Last year, I wrote about various clusters:

http://cembalobill.blogspot.com/2009/06/clusters.html

I did not go into what must be done to change the 3YF transmission into a 4SU unit.

3YF is the XTZ , the engine used in all MuZs, 4SU is the Belgarda SZR and the engine used in that bike which was assembled by Minarelli in Italy. Minarelli also builds the new 4-valve XT660 engine.

In that posting, you can see the different ratios and that the only difference between the 3YF and 4SU is 1st gear. Everything else is identical.

So, for those MZ riders desiring the better cluster (that the Skorpion should have had to begin with!) the easiest way to go is to obtain an SZR cluster thru eBay or similar source. They are not offered very often, however, and the price can be unrealistic as are the prices of many XTZ parts at eBay.

Lacking the complete cluster, one can order the mainshaft and loose 1st gear for the 4SU from any Yamaha dealer:

Mainshaft: 4SU1740100 list price 125.00€

1st. gear: 34K1721100 list price 40.00€

This is a 4SU cluster. The mainshaft is at the top, 1st gear at the right on it. This gear is milled directly onto the shaft. That is why the mainshaft must be exchanged. 2nd gear at the far left is pressed onto the mainshaft. This presents the main problem when rebuilding the 3YF cluster with the 4SU mainshaft. A suitable press is mandatory and one must make (or find) a piece of steel pipe into which the whole mainshaft will fit, allowing 5h gear -second from the left - to rest on the rim of the pipe. Thus set up, the shaft can be pressed thru the 2nd gear and fall free.

All the parts can are then assembled in the same oder onto the new mainshaft and the 2nd gear pressed back on. For this job, it is best to have a different piece of pipe into which only the shaft itself fits, allowing 1st gear to rest on the rim. Being observant of course, one will have measured the axial tolerance of 5th gear to turn freely as well as the exact amount the shaft stands proud of 2nd gear. Turning a small piece to fit exactly flush with the end over the shaft before disassembly will make assembly nearly fool-proof.

I have reassembled several Skorpion clusters with the 4SU mainshaft and it is not higher science but you do need, as I said, a suitable press and the mandrills to insure the the parts are moved straight. It is not necessary to heat the gear at all.

Bottom line:

As I have repeatedly written, it is a must-do for anyone riding a Skorpion hard. Apart from needing to the break the engine completely, the actual job takes only about 30 minutes, a couple of cheap and easy pieces of pipe, a lathe and the press.

The total cost for the parts (here in the EU) ±170€ plus the scraps of pipe. 200€, even 250€ are thus acceptable for a used cluster in good condition if one does not have the machineshop at hand.

If and when one does get into this, one could consider going for a shorter 5th gear; see chart below.

Slipstream offers (or at least offered the pair of gears for 270£. Here in Germany, Joachim Pethke has made pairs and such pairs do turn up in the ESA (european supermono assoc) scene.

I am using a used pair myself.

Obviously, the pressing is the same to change 5th.

At one time, OVER made racing clusters for the XTZ engine, used both by theirselves and marketed as Yamaha works clusters. These cost 2500DM in the 90ies. They now generally go for over 2000€.

Koehler here in Germany made clusters for MZ and these very occasionally turn up. I have installed one.

Slipstream offers (-ed?) a close ratio cluster as well, on my dated price list at 1500£.

Again, the ratios of the OVER and Koehler clusters as well as the shorter 5th gear are on that chart:

I do not recommend either of the race clusters for street use; I have extensive experience with the OVER myself.
For serious track outings, tho, they cannot be beaten if the motor has been freed up and the ignition suitable without rev limiter.
For street use and the rest of us (including me now) the longer 1st of the SZR together with a shorter final ratio opens up a whole new world of fast Skorpion riding - and big game chasing.

Oh, and one more thing, another important must do for anyone running the 3YF or 4SU hard:
One must replace the gear on the crankshaft for the balance shaft with either that of the new
XT660 part no. 5VK-E1536-00
or of the Raptor 700 pat no. 1S31153600
Both fit, Shown in the picture here:

is that for the Raptor. The XT660 gear is a 1:1 replacement; the thick steel washer behind the gear must remain in place.
The Raptor gear is as much thicker as the washer is thick, so the washer must be removed. The gear as far as size and module is identical. I prefer this solution.

2010-08-21T23:54:00.000-07:00

Update:

Now that the 1000km break in are done, I can push it as I am used to doing. The oil tank is a complete success. I already wrote about the temperature in actual use. One thing I could not judge before now: I use practically no oil now. This can only be attributed to the form of the tank, i.e. to the fact that the returned oil does not foam up and is allowed quietly sink to the bottom of the tank. Also the oil itself is still recognizable as having been red when new. It is of course dark greyish red, but not opaque black at all. This is still the first filling for the new engine. I admit that I have not changed it yet, something I normally would have immediately done after the break in. It is Castrol Power Racing 1 10W/40. I use a K&N #145 oil filter. I also always add 2-stroke oil to the gas, always fully synthetic, usually Castrol, but most any will do actually. About 25cc to the 15ltrs filling.
This engine is definitely better than last years aircooled and I think perhaps the my best street-use engine to date. I can live with the vibes which are nowhere near bad as with the balancerless engine of the blue bike.

----------------

Today, after finishing the parts I need for the customer engine on the workbench and mowing the lawn (brownie points!), I went for my usual ride in the Swabian Woods (Schwaebischer Wald) which take me up what was the official Heilbronner Bergpreis (hill climb stretch, was a national event until 1983) and on to Sulzbach an der Murr, turning towards Schwaebisch Hall on the B14 (national highway) which is a favorite "hill climb" because it is relatively new and in good condition and because there are almost never any sheriffs present. Who knows why...

I take this to Mainhardt and then turn onto the B39 back towards home. coming by the "Loewensteiner Platte" where I usually stop for a coffee if it is not too full.

Despite the good weather, there was still room to park which I did and immediately caught notice of three Vuns! Three of a bike you normally do not see once a year around here!

This is Cristina Baio: 2004 champion, Italian female superbike series, Hers was one of the three Vuns there.
A friend of mine, Oliver Thiel - Ollie - instigated this. Since I last talked to him, he has gotten a CR&S consession (and sold a Duu that is not even on delivery yet) and had been at the Nuerburgring with some Vun owners the day before. One of the three present was his demonstrator, the others, that of Cristina and of John van Houten.
Ollie greated me with, "grab your helmet and take it out for a test drive." Didn't need to be told that twice; not all that often you get a chance to ride something as exotic as a Vun.
What can I say? It looks and feels very light. Actually, tho, it is only a couple of kilos less than my Skorpion SP. Riding position is good: this is very first bike with a super bike bar (ape hanger in my eyes) that I actually liked. I later rode John's which has LSL clipons and it was MUCH better. The BMW Rotax has quite a bit of punch up to about 6500 and is easier to drive at 5000 than my engine, but it is not at as good at low (2500-3500) or high and is probably down a bit on top end performance. No measurements, just my very subjective feeling. The Brembo radial clamp with racing pads is decidedly 1-finger only but easy enough to use and VERY effective. Biggest impression for me, tho, are the BST CF wheels. All three Vuns had these wheels. Steering, braking and acceleration are all extremely quick, seemingly effortless. These wheels are becoming a obsession with me. They would bring the weight of my bike down to 140kg, reducing the weight where it counts most. Costly dreams............
After more discussing at the "Platte" we rode together to Oillie's shop, John with mine and I with his. Riding home from there, that is riding mine after just having ridden the Vun, was a pleasant surprise.

I had lots of fun with both Vuns. What I did not like? The throttle response from idle in and around town/street use is very grabby, to put it mildly. I am used to flatslides and they are quick, but this was extreme. I would probably get used to it after a day or two. OTOH, I might possibily dump the injection for dual flatslides... I would definitely want narrow clipons like my Gilles GP Lights and also a smaller Ø front wheel pump. And of course I would reverse the shift pattern as always.

What else I liked?
My own baby was not so far off from this highend product. Franco (from CR&S) in particular was quite impressed with some of my technical stuff and took a lot of pics. He was pleased to see that I had somany Poggipolini products on mine as he a the owner are friends. John commented (he rode mine) that it immediately felt very light and that the steering was extremely light. He wasn't fond of the vibes but then he didn't get a chance to really rev it out and shifted far too soon. After riding he also commented on the very quick throttle response and ease of riding on residential streets and he found my riding position good.

Unlike so many things I have test ridden that were hyped up by the press, the Vun is not a let down at all. I am not sure it is a must-have, but it certianly comes close. Given their policy of building to customer specification, I can readily imagine that "my" Vun would be exactly as I want a bike to be. Things to dream about...

2010-07-03T00:44:00.000-07:00

Picking up from the last entry, the bike is running and passed MOT without any trouble at all. I did cheat by installing the the quietest DB eater - which I then removed right after MOT.

It took ages to get the 101 Wiseco flat top piston. The barrel was bored and honed to 101.05. I needed to make a 1,5mm alu spacer under the cylinder to match the compression height. The cylinder (3AJ), which I got "as is" with the XTZ (3YF) sleeve in place, was turned on a lathe after shrinking in the liner. Obviously, a little too much had been removed. No problem, tho.
The head (2KF) with the new valves from GS Valves fits of course. As before, I am using the beehive springs from RD.

From my "collection of cams" ranging from stock to Megacycle 266/4, I chose the 266/4 because it is a billet cam. Thus the rockerarms do not stand at such an adverse angle to the valve stems and they normally do with "reground on customer core" cams.
I milled the mating surface of the Y-manifold so that the carb doesn't hang as low as it did, leaving at least a little room between it and the plus connector of the starter.
Otherwise everything is as before or as described recently.
I actually did get the tiny LiFePo battery

I mused about. Although it is rated only at 4.6Ah, it delivers 150A start current or more. It weighs in at 650grams instead of the 2700grams of the Hawker placed next to it to get an idea of the size.
If anything, the motor (remember, no deco!) starts better than with the Hawker SBS8.
Tuesday, after it was back together, the first attempt:
-two twists of the grip for the accelerator pump to squirt some gas in;
-pulled choke;
-turned on and pressed the botton;
-WUMS! at the first turn.
In this warm weather, it starts without the choke.
So at least it does start and the battery is indeed strong enough.

The oil tank I talked about at length last time looks to be a success. Summer weather, hot (for here) with temperatures above 30ºC, stop and go and traffic lights; I measured the oil temperature immediately on return and it was 105ºC. at the top, i.e. the oil coming from the engine. dropping to about 90 at the bottom. There is no foam visible and the oil is still remarkably clear. Remember last year I never got over 80ºC. I did stupidly have an oil cooler because I listened too much to others and did not think for myself. 80ºC ist simply way too cold for modern oils. No wonder the SRX/XT clan think 30000km is a good distance for an engine!

So the new cylindrical oil tank does manage the oil better and it also contains more oil.

Now to drive in the new rings and valve stems and take it from there.

I am pretty sure the present can is not the best there is. For MOT, I had inserted the longest DB eater and the motor was unwilling even at 6000, also starting more poorly and idling roughly. With the shorter pipe, everything improved greatly yesterday.
When I have run in the rings, I can test for performance above 7000. Last year's engine would not turn above 8000. Quite posssbly the the small TM40 carb is just too small. I plan to try a TM42 but probably there will be no way around fitting a TM34-B65 on longer intake pipes. Before any of that, tho, I will probably get that SR-Racing can($$$) I wanted all along.

anything else just now?
I drove over to the farmer's cooperative in the next town where I can weigh my bikes on their scales inside, the one use for pallets and bags, not the big truck scales outside:

148kg = 326lb with half-full tank.

We're getting there...

here is a little demonstration how fast it starts when cold:

A few people who bought the TCIP4 have complained about their bike's poor starting and were wanting to blame that on the iginition, especially the last setup I did with it. I have the TCIP4 with the last setup and there can be no question about poor starting here. No choke was used, just one or two squirts with the accelerator pump and then pressing the button which I do with the left hand normally so that I can immediately respond with the twist grip. When cold, idle with the reather extreme cam is anything but good and short gas bursts are necessary usually to keep it alive for a short time at least.

Update SP 2010

2010-03-20T02:52:00.000-07:00

Long time since I've updated here. There has not been too much to tell since the last time.

For several reasons, I dismantled the Skorpion last November. Most important of those was the wish to pursue the air-cooled engine further. But there was also the the racing cluster to contend with. After the season's use, I had to admit that as nice as the cluster was in high-speed use, it was very trying in everyday traffic. Thus, I removed the engine completely and exchanged the OVER cluster for a standard SZR trans, albeit with a shorter (ex-Kehrer) 5th gear. I also exchanged the right crankshaft ball bearing for a roller bearing.

When I reinstalled a lightened balancer last year, I replaced the original drive gear with the cushdrive for a solid gear.

The cushdrive is the main reason for the abnormal deterioration of the woodruff key in the crankshaft. This is the case when the engine is pushed very hard, particularly downshifting into corners at higher RPM. The cushdrive stores the energy of the balancer shaft and gives it back to that key. The solid gear behaves better and the engine runs quieter as well.

Last year's engine was based on an early TT bored out to 98mm. While this ran well enuf, upon dismantling I saw that the changes Yamaha made between the early versions and the last ones were necessary. These are changes in the oil feed and heavier (9mm instead of 8) head bolts with a wider spacing. The E-start motor also has no manual deco. I put the TT head and cylinder out to pasture. (=trash)

This year I have a last version XT600E cylinder with 100mm XTZ barrel giving me the original 660cc. The head will have custom-made valves from G&S Valves . As in my blue bike, I will use a probably a stock piston with a stage 2 cam shaft and the RD beehive springs I had in the TT head. The Grizzly manifold with 40mm Mikuni will also remain. I also have a TM42 which I may just try out. Basically, tho, the engine is similar to last year's but with 660cc.

The Skorpion's plastic oil tank has long been a sore point for me, not so much because it is plastic but because of its shape. So this winter I decided to finally do something about that. I measured and pondered and came up with a cylindrical aluminum oil tank , as high as possible to fullfill the standard requirements that an oil tank be at least 1/3 larger than the filling.

This is an example of a typical car dry sump oil tank. Much higher than wide, notice as well, that the return connection on the side at the top is not centered. Rather it is "tangential" so that the return oil stream runs along the inside wall to the bottom to help prevent foaming.

Here is another state-of-the-art example of such a tank installed with a racing V-8, the brand-new Roush-Yates built Ford 360 for sprint car racing.

Unfortunately even the smallest of these readily available tanks is much too large for the bike so I "designed" one myself from 140mm Ø aluminum pipe and 4mm sheet material. It hangs on the two front seat mounts of the seat frame (orignal but much modified) and is supported by the two back airbox grommets to which the battery box was attached before. The airbox was thrown out years ago.

I turned an aluminum fitting threaded to accept the Skorpion filler cap and modified the in-hose sieve fitting to be welded onto the bottom of the tank. The oil feed line connects to this and runs straight to the engine. The return line which cannot really be seen here, runs up to the return connector on the left side at the very top of the tank.

The filler cap fits so closely under the seat, that it cannot unscrew even if it is loose. Several riders have lost that filler cap from the OEM tank; I know at least one rider who has a separate heavy wire latch to prevent it from unscrewing. I needed a new cap because the red one shown here which fits the aluminum part would simply snap loose if tightened even a little bit too tight.

With the OEM oil tank gone, the seat frame is empty. I am in the process of making a prototype shallow pan of 6mm waterproof plywood to fill the entire space, utilzing the three bolts of the OEM tank. All the electrical stuff except the rectifier, which you can see in the bottom of those three pictures, will be placed on this pan which should protect it from the weather keep it relatively clean. The pan will close the to seat frame underneath. When I am satified with the pan design, the prototype will be replicated from sheet aluminum and anodized black.

My harness is home-made anyway as I must have related more than one. I use the Silenthektik solid state fuse box with blinker and ignition relays. I also use an Ignitech rectifier and the Ignitech Sparker TCIP4 ignition box. The ignition key is on the right side below the seat and switches a Bosch 16A. relay which turns on the +12V. main to everything but the starter.
In the meantime, I have made a prototype tray of 6mm waterproof plywood; easy for me to do and easily modified if necessary. When I am satisfied, the prototype can be replicated in aluminum or fiberglass.

All the electric stuff is placed together as one can see. The space in the seatframe is entirely filled. The underside of the tray is clean; apart from the reservoir for the strut, there is nothing there.

The side view is completely clean and unobstructed.

Of course the exhaust system is still missing.
When I do make the aluminum tray, the arrangement of the parts will probably be different. I intend to use a LiPo battery. As soon as the bike is running, I plan to test what minimum size is necessary to start the engine which has no decompression unit.
If possible - it is a question of height, the LiPo battery will be set at the front end of the tray, right behind the oil tank and as close as possible to the rectifier and ignition switch. The SilentHektik unit would then go roughly to the place the big battery now occupies. Of course the LiPo battery could go where the Hawker is at the moment.

to be cont'd.

Update

2009-07-31T09:17:00.000-07:00

I have chosen to call my present one-off Skorpion a Skorpion SP.

A few may have noticed in the last update that the Skorpion has new rearsets. As of this month, Gilles Tooling is officially offering rear sets specifically for the Skorpion. Together with Gilles, I put together a set using parts from their well known highest quality line. As with virtually all available models, this one also uses some parts common to many bikes. Each part can be individually reordered if needed. Both shift and brake levers are ball-bearing mounted, each with two bearings. The pegs shown are the new model which is slightly smaller and lighter than the old-style peg, which, however can also be had if desired. In fact all four sets mounted in the last two weeks had the old-style pegs.

The mounting plates are specially for the Skorpion and the model designation is AS31GT MZ01R. The pictures show my prototype set utilizing mounting plates for a Triumph with however did not fit exactly, I remachined them. The MZ01R set has plates machined to fit.

They come complete with all parts and bolts. Included but not shown here is the lever for the engine shaft, also CNC machined from aluminum and with two different possible lengths. As can be seen, the shift lever has three different ratio lengths. Thus, one can set the shift lever from virtually no travel to quite a lot. I have first gear up but of course the "normal" set up with the transmission shaft lever facing down is just as easily possible. The rear sets shown are titanium colored, but black or gold are also available.

Rearsets for the Skorpion Replica will be coming up soon.

These rear sets can be ordered from me or, of course, directly from Gilles.

I have now also fitted the the intended exhaust. As I mentioned in the last posting this has "Devil" performance headers with spring retainers. Mated to this is the LeoVince can for the TT 600 complete with its connecting tube. I made no changes to any of these parts! Together they fit almost perfectly. In the lower photo you can also see the old-style pegs which I had mounted to show. I personally prefer the new ones.

I have continued to prune and trim; after due deliberation I decided to remove the cross-tube above the cylinder head from the frame. Not for weight, I did this to finally be able to easily get at the engine. Now I can remove the cam cover or even the whole cylinderhead and cylinder from the installed engine without even removing the front down-tube, let alone drain the oil.

Bliss!

So easy to work on. And, I can tell no difference in handling without the tube, even with a tank top bag and heavy back pack, coming back from our yearly meeting.

I have in fact removed the head since cutting out the tube.

After the engine was run in, I removed it and took it entirely apart to check for undue signs. There was nothing alarming anywhere. At this point I did reinstall a balancer shaft, albeit a much lightened one and a solid drive gear for it as well.

The often mentioned problems with the woodruff key in the crankshaft are caused for the most part by the spring cushdrive in the drive gear. With the solid gear, the engine runs much smoother.

What else have a I changed?

Hardly worth mentioning, I exchanged the Brembo steel semi-floating rotor seen above for a full-floating cast iron rotor - Brembo of course. I think there is a big difference, at least with the Carbone Lorraine C55 pads I use.

Most Skorpion riders will have been bugged by the poor solution for retaining the gas tank. If "lucky," the bolts cannot be removed at all. While that is not the case with this particular tank, it was with both of my other Skorpions. I decided it was time to come up with something better.

This is a small snap lock from "Camloc." it has a safety catch. I made a piece from 1,5mm stainless sheetmetal to rivit the lock to and screwed this with spacers to the bolt holes of the tank. I cut open the two grommet retainers at the top so that the tank can be simply set in. the lock catches to the edge of the original bracket. (see also picture of rectifier farther down.)

No more bolts to undo or maybe loose; unlatch and pull the tank off - if you have a quick-release connector in the gas line like I do.

I also got very tired of unscrewing the seat - such a pain in the ...
"Camloc" again: I obtained their "Dus" fasteners and am using just one to hold down the seat. Sheet stainless again, i made the bracket for the bottom of the fastener ad rivited it to the seat frame. The fastener bolt with its retaining wahser were then marked out and drill through the seat and pressed in.

Just one half-turn of the latch and the seat can be lifted off.

To position the seat, I simply screwed all four M6 bolts - Poggipolini aluminum screws into the threaded sockets for good. Their tapered heads make fine positioning pins after their holes through the seat were reamed to fit with a tapered reamer. The front two screws can just be seen in the picture below as well as the latch for the tank.

During the yearly meeting my rectifier went bad - for the second time on this bike.

Maddening!

I did manage to limp home, running without the lights and charging the battery every nite.

I have replaced it with the "Charger" from Ignitech, seen at the right. Not a whole lot to see but it is very well made (just like the ignition box mentioned in the last posting) and comes plug and play if desired and specified at ordering. Since I do not have an OEM wiring harness, I got it standard. I simply cut a a piece of 4mm aluminum sheet, drilled it to fit the tabs of the seat frame and tied the rectifier to it with two binders.The rectifier has no mounting holes of its own but it is profusely ribbed. It works great and does not even get hand warm. I can supply both the "Charger" and the "Sparker TCIP4" ignitionbox which I normally supply preprogrammed for the XTZ engine, depending on the state of tuning.

Oh, in the last posting I said I 'd weigh the bike ASAP;

I did at the farmer coop: 152kg ready to ride and gased up.

Clusters

2009-06-06T09:42:00.000-07:00

I mentioned the OVER works cluster I have.
In the past I have often recommended changing the XTZ shaft for that of the SZR in order to gain a longer 1st gear.
The two new engines mentioned in the last posting also have been changed. One of them has the SZR shaft and first gear, the other has an ex-MZ works racing cluster made by an east German machine shop for MZ. It differs slightly from the OVER.

Here are all four clusters:

You can see how rediculously short 1st gear is in the XTZ engine. Belgarda changed that for the SZR, leaving the rest alone. Both racing clusters are very different from stock, with extremely long 1st gears and close ratios. The OVER cluster is most extreme, being even longer in 1st and shorter in 5th. There are only about 800RPM between shifts which is perfect for racing but can be very trying in regular driving and downright exasperating in traffic. Speeds below 25MPH are only possible with a slipping clutch.
Having tested the ex-MZ cluster as well, I can say that it is only slightly better on the street. Both shift by themselves, fast and effortlessly, up and down without the clutch.
This of course has to do with the higher quality of the cluster itself, but more importantly with the small difference of speed between the two shafts. That is the reason why the SZR cluster also shifts better than the XTZ. The layshaft is driven by 1st gear, so the extremely low 1st of the XTZ makes the speed difference large. The slightly longer 1st of the SZR greatly improves the shiftability, and the extremely long 1st of the two racing clusters makes shifting nearly unconscious.

The OVER cluster is different in another way as well.

Here you can see both an SZR at the bottom and the OVER cluster at the top. You can see that the gears look different, and that 4th and 5th have coarser, stronger teeth and are considerably wider than the stock. The dogs are different as well.
The ex-MZ cluster does not use two different modules.

The OVER is no longer made and the ex-MZ was never offered as such. Reportedly, the machine shop which made them would make more if demand arose. Slipstream does offer an racing cluster. All of these, foremost the OVER, are or were very expensive. Slipstream also offers a shorter 5th gear.
More important though, for the "normal" Skorpion rider is the modification with the SZR shaft and 1st gear. This is a simple and worthwhile modification. For me a must-do.

update

2009-06-06T08:30:00.001-07:00

I haven't written anything for a while; not a whole lot to tell really, at least not with regard to this blog.
I did build up two moderately tuned XTZ engines for Skorpions and also got around to a first stage of my pet idea, an air-cooled Skorpion. The original Seymour Powell design project had the 4-valve air-cooled Rotax engine which MZ was already using in their so-called Classic at the time.
I chose to stay with what I am familiar with, i.e. with Yamaha and assembled a bastard engine utilizing the XTZ crankcase of my racing engine with its one-off welded crankshaft with Carillo, the OVER racing cluster, and my own rollerchain timing gears (December 2007). On top of that I put a TT cylinder, bored out to 98mm with a Wiseco racing piston and a TT head with minor porting and a Megacycle 266/20 cam and RD's new Beehive springs.
These are very impressive to me. The pressure curve seems flatter, more constant and the dry engine turns over lighter by hand than with the more usual racing springs. The springs are 30% lighter even with steel retainers than the previous sets with Ti retainers according to RD.
Basically the engine looks like this now with a Grizzly manifold and Mikuni TM40/6:

Not needing a water pump, I turned an aluminum cover for that. The water pump drives off the crank at 1:1. I plan, when I find time(?), to make a timer with pickup for this position so that I can use any after market ignition and set the static advance as I see fit. That will also allow me to adapt a smaller lighter flywheel since the OEM pickup will no longer be necessary.

Installed in the bike, we now have this:

The oil cooler is from XJ600, the leads are new as is the direct feed to the camshaft. the exhaust manifold is from Devil for a TT. Suprisingly, it fits the Skorpion frame almost exactly.

For the time being, however, I have adapted the Skorpion's original Lenhart und Wagner exhaust system to fit the TT head.

There will be a SR Racing can eventually matched up to the headers shown above.

As with my Yamaha, I use an Ignitech Sparker TCIP4 programmable iginition box. Both of the aforementioned XTZ engines also use this box.
The bike started right up and all the new oilsupply lines are tight; everything is dry. Now to test ride and above all to break in the new barrel, piston and cam.

During the winter I will dismantle this engine again and install a new crank. This is what my pet idea is really about. The new crank will have 10mm LESS stroke, have a 5mm longer conrod and be lighter. Barrel and piston will remain as they are now, reducing the capacity to 560cc from the 630 I now have. A much lighten balancer shaft will also be installed, together with a solid drive gear for it. Both of the new engines mentioned above have these solid gears, one of them a lighter balancer and that one in particular is "smooth as silk." The lighter generator will also contribute (I hope) to making an engine with a much higher usable rev-range and ( I hope again) not much less performance, if at all.

The Czech ignition box has proven to be a real improvement. The advance curve of the DENSO box is too extreme of anything bu the stock engine and even the stock engine benefits from less advance above 1000RPM. In the stock Yamaha SZR, I have the box set up to a maximum advance of 28º at 6000RPM instead of the 37º of the OEM box. The limiter ist set to 9000 and I regularly rev the stock engine in 1st, 2nd and 3rd over 8000. Instead of wasting money on having the OEM box modified as most do ( and I did as well when I didn't know better!) it is definitely better to buy the Ignitech Sparker. The price is another argument for the Sparker and the support from the company couldn't be better.

Like my earlier blue Skorpion, this bike also has the Brembo TZR wheels that the Skorpion prototypes had: 3"/17" front and 3,5"/17" rear. I am testing the Haidenau Cup racing tire in 110/70 and 130/70. The first few miles were very encouraging: light-footed as a bicycle.

L
I will update about the aircooled Skorpion as time goes on. Next week I will definitely get it on the scales.

more on ridig position, this time in German

2009-04-19T02:39:00.000-07:00

Hang off, ein "Predigt"

Die geneigte Achse des Fahrzeuges in einer Kurve, die immer gleich ist bei gleichen
Bedingungen, ist nicht unbedingt mit der Linie durch die senkrechte Mitteachse des Fahrzeugs identisch. Im Gegenteil; sie ist es nur, wenn das Fahrzeug senkrecht steht. Sonst ist sie die Verbindung der Mitte der Kontaktflaeche und des Schwerpunktes des Fahrzeugs. bei gleichem Schwerpunkt aber breiteren Reifen dreht sich diese Linie entgegen der "Schraeglage," was zur Folge hat, dass die physikalische Schraeglage gleich bleibt, also diese Linie durch Kontaktflaeche und Schwerpunkt mit Fahrer, aber die Schraege des Fahrzeuges selbst groesser wird. Eben diese Erscheinung begegnet man durch das Hang off, was ja den Schwerpunkt des Fahrzeugs MIT Fahrer nach innen verschiebt, also die Schraege des eigentlichen Fahrzeugs mit der des Gesamtsytems Fahrzeug+Fahrer annaehrt.

Krasses Gegenbeispiel, ein Fahrrad: hier hat man einen sehr hohen Schwerpunkt und einen sehr schmahlen Reifen, dessen Kontaktflaeche kaum aus der Ruheachse wandert. In diesem Falle ist die gefahrene Schraege praktisch identisch mit der Theorie.

Nimmt ein Blatt Papier und zeichne eine Waagerechte und eine Senkrechte darauf. Nun male einen Kreis mit 15mm auf die Waagerechte, mittig um die Senkrechte; ein 150er Reifen. Nun, einen 80mm Kreisbogen mit Mitte im Schnittpunkt (A) der beiden Geraden. Der Schwerpunkt bei angenommene 80cm ueberm Boden. Nur eine Annahme; hier geht es nur um das Prinzip. Nun mit dem Geodreieck oder frei-Schnauze eine Linie (A-B) mit 30º aus dem Schnittpunkt A: eine theoretische Schraeglage. Nun noch eine Gerade (C-D) mit 30º von der Mitte der Kontaktflaeche - kann man an Hand der 15mm Kreises abschaetzen, oder wer es genau will nimmt 1/6tel des Umfanges (15*3.14/6) neben dem Schnittpunkt A. diese Linie C-D liegt aber neben dem ersten Schwerpunkt B, wenngleich auf dem Bogen der den Schwerpunkt darstellt. Diese Linie C-D naehert aber der phsykalischen Schraege an. Wenn man nun aus dem urspruenglichen Schnittpunkt A durch
den Schnittpunkt D des Bogens mit dieser zweiten Schraege C-D eine dritte Schraege A-D zeichnet, kann man leicht sehen, dass diese Linie - die eigentliche Fahrzeugachse - schraeger ist als 30º. Das ganze kann man leicht mit einem 12mm Kreis = 120er Reifen und einem 18mm Kreis = 180er Reifen wiederholen um die Aenderung der Linie A-D Kontaktflaeche/Schwerpunkt zu beobachten.
Hangt nun der Fahrer off und legt sein Gewicht nach innen, wandert der Schwerpunkt des Gesamtsystems auch nach innen Richtung der Linie C-D. Um diesen Versatz veringert sich die Schraege des Fahrzeugs. Aber die theoretische Schraege von angenommenen 30º fuer das Gesamtsystem bleibt konstant.
Bitte, ist sehr vereinfacht.

Eine Anmerkung in Zusammenhang mit hang off; Viele sprechen von "...sitzen..." und da liegt das eigentliche Problem: bei korrektem hang off sitzt man nicht, man hat das meiste Gewicht auf den Rasten. Drum muessen die Rasten weit genug vorn sein und der Sitz nicht zu schmahl oder zu weich; der Sitz dient am meisten dazu, den Bock zwischen den Schenkeln zu begrenzen, aber man belastet nicht wirklich den Arsch, man laesst dem Moped soviel Freiheit wie moeglich.

Noergler sprechen vom Turnen, Rumturnen, gar abschaetzig in manchen Lagern von
Rumhampeln, aber es trifft's recht gut. Der Stil ist nichts fuer Touren, er ist auch sehr anstrengend und braucht Kondition. Aber traeger ist er nicht als klassischer Knieschluss, und das vermaladeite Runterdruecken, bzw. Gegenimpluslenken ist, schon aus physikalischen Gruenden, potentiell viel traeger. Gefaehrlicher ist er allemal.
In diesem Zusammenhang; ein anderer hat angemerkt, dass dass es zu lange braeuchte, aus der "abgehangenen" Haltung wieder zurueck zu kommen, also von einer zur anderen Seite oder wieder in die Mitte und deshalb fuer den Alltag und in Notsituationen nicht angebracht sei. Oder so aehnlich.
Lassen wir den alltaeglichen Nutzen.
Wenn aber man zulange braucht, macht er entschieden was falsch dabei. Ich tippe darauf, dass er sein Gewicht nicht auf den Rasten, insbesondere auf dem kurven aeusseren Rasten hat, also dass er mehr oder weniger immer noch sitzt, wahrscheinlich auch den Koerper in einem Kreisbogen, von oben gesehen, um die Lenkachse dreht, anstatt gerade seitlich hin und her zu rutschen. Die Hauptursache hierfuer sind die Rasten selbst, die fast immer zu weit hinten sind. Die alte "sportliche" Sitzposition mit lang ausgestreckten Aerm' und Rasten weit hinten taugt nur fuer den klassichen Knieschluss. Sitz mal auf eine aktuelle Superbike (e.g. R6 oder Gixxer); Du wirst erstaunt ob die kommode, fast tourenmaessiger Position, Rasten ziemlich weit vorn aber auch recht hoch, alles nahe am Lenker. Die Position muss so sein, dass man ueberm eigenen Schwerpunkt sitzt, ohne das Gewicht des Oberkoepers auf den Lenker abstuetzen zumuessen.
Beide Fahrstile, Knieschluss und Hangoff, lassen sich nicht kombinieren. Immerhin, der absolut unknackbare Nordschleifenrekord haelt der Daehne - mit 18" Trennscheiben diagonaler Bauart. und mehr oder weniger mit Knieschluss.

Nochwas: ein dritter Punkt im Sinne des Fahrzeuggewichtes sind die Knie nicht, stabilisieren aber sehr wohl die Schraeglage, besonders bei schlechtem Belag. Und sie geben Information ueber die momentanen Schraege, die z.B. bei nach aussen abfallenden Kurven optisch taeuschen kann. Sie sind aber nicht die Notbremse oder die Anzeige dafuer, das es reicht. In sehr schnelle Kurven oder solchen die eine grosse Schraglage zulassen (z.B. 180º wie Sachskurve oder Lausitzring Infeld) wird das Knie wiedereingeklappt, weil es dafuer keinen Platz mehr hat; die Notfunktion uebernehmen die Schuhspitzen. Auch ein Grund warum die meisten mit erstem Gang oben fahren. Und beim rausbeschleunigen richten man das Moped nach und nach auf zwischen den Schenkeln, OHNE die Hang off Haltung zu aendern oder gar zu verlassen, um dem Gripverlust beim Beschleunigen zu begegnen, aber auch um das Vorderrad mehr zu belasten. Beim Knieschluss kann man so was schlicht nicht machen. Da ist das System Fahrzeug/Fahrer zu traege. Auch beim Reinbremsen ist es aehnlich: das mehr oder weniger senkrecht stehende Vorderrad rutscht bei weitem nicht so leicht unten weg = lowsider.

Es wird behautet, dass man relativ gleichmäßigen Haftungsverlust mit dem Knie abfangen kann. Nur bedingt; eher handelt man sich einen lowsider damit ein. Driften benoetigt, ja bedingt weniger schraege. Dagegen kann man einen potentiellen highsider - wohl gemerkt nicht immer - eben dadurch begegnen, das man das Moped einfach machen laesst.
Highsider auf der Rennstrecke kommen meist beim Rausbeschleunigen aus der Ecke wenn das Hinterrad voruebergehnd Grip verliert infolge der einsetzend Leistung und zum dem Zeitpunkt als mehr Koepergewicht auf dem Sitz liegt und das Moped eben nicht zwischen den Schenkeln austoben kann.

Durch die Kreiselkraefte ist das Moped zunaechst inherent stabil. Die Unruhen werden von aussen primaer durch den Fahrer eingebracht , und dann die auesseren Bedingungen wie Belag, aber auch bei Strassenfahrzeugen durch technische Unzulaenglichkeiten wie ungeeigneten Reifen, schlechte Lenkkopflager, falsche oder falsch eingestellte Federelemente u.ä.m.
Natuerlich kommen Highsider auch, besonders auf der Strasse, beim krassen Belagwechsel wie vom griffen Asphalt zu Bitumen und dann Asphalt wieder und da ist man meist machtlos.

Nochmal zur Schraeglage selbst: je hoeher der Schwerpunkt aber auch je schmaeler die Reifen, desto weniger die Schraeglage fuer die gleichen Bedingungen. Also z.B. mit einer srx. Beides: schmahl und hoch. Oder einer Koenigswelle 900SS: vorn 100/110-18, hinten 100/120-18... die Ur-Superbike.
Was den Reifen angeht, bei zunehmender Breite wandert die Kontaktflaeche aus der senkrechten Achse , je mehr Schraeglage, desto mehr und dies bedingt eben mehr und mehr hang off.
Schon deshalb sollte man die SZR oder Skorpion mit 140er Reifen hinten fahren..

German MOT

2008-05-30T00:55:00.000-07:00

today a short rant - or more correctly sad story with a happy ending about my attempt to go thru German MOT (TüV = technischer Ueberwachungsverein) with my green Skorpion.

My German text is attached.

Last week, I took the bike to a local car mechanic shop (good one) where the TüV person comes every Tuesday.

I laid out the paperwork (registration etc.) but he didn't even look at that. Went out to the bike and starting at the front, once he was satfied that all the lights work, critized:

-the headlight is not original - it is in fact, unlike what was originally in bike;

-footpegs don't fold up - no they don't and never have and I wouldn't have a bike that does. The rearsets are listed in the registration that he didn't look at.

-What silencer ist that!? what can I say - the absolutely original L&W

-Where's the certificate for the carbon fiber hugger?

etc etc etc.

Ended with, "I refuse to renew the MOT. Nothing but the frame and engine are original on this thing."

Well, the frame is one thing that is original MZ alright but definitely not stock; it is frame number 004, the first prototype frame for the Replica that the good people at MZ decided was too light and weak. No need to go into the engine.

I have attached scans of the registration certificate.

The most important part is the second page on which is flatly stated that,"this certificate was issued to Heinz Weber(etc) for the vehicle made of MZ parts which he has built himself. This certificate was issued on 15.06.1998 vom TüV Verkehr und Fahrzeug(traffic and vehicles) official techical inspector "Ochs" (his name)."

The other pages list all the stuff that differs from the Skorpion and, on the third page, "Parts and frame MZ Skorpion Replica."

Like I said, he didn't even bother to look at at that.

Yesterday, I tried again, this time at a different shop with a different inspector.

What can I say? He actually checked a lot more than other guy, actually looked at the registration and gave his OK without reservation.

Same bike a week later!

---------------------

original text:

Beim Treffen habe ich vom mislungenen Versuch TüV zubekommen erzaehlt.

Vorm Treffen war ich deshalb bei einer Autowerkstatt hier im Ort, zu der der TüV Mensch ins Haus kommt.

Angefangen hat's, nachdem er die Lichter auf Funktion geprueft hatte, vorn mit der Meckerei:

-der Scheinwerfer ist nicht original - tatsaechlich ist aber wirklich original, das Glotzaugeding, das nichts taugt

-die Fussrasten sind starr - die sind eingetragen

-Was ist das fuer'n Daempfer? der voellig originale L&W, nicht irgendwas lautes wofuer ich evt. bekannt waer.

usw usw usw.

Letztlich sagte er, " Das Ding nehme ich nicht ab!, Da ist nichts ausser dem Rahmen und Motor original."

tja. Ausgerechnet der Rahmen, der mit der Nummer 004! von MZ aus dem Versucht stammt.

Sachverstand?

Bleibt noch nachzutragen, dass er den Brief (siehe jpgs) gar nicht erst angesehen hat.

Gestern neuer Versuch, diesmal bei meinem Lackierer, Juergen Bender, da ausnahmsweise der DEKRA Mensch wegen eines Anhaenger zu ihm ins Haus komme.

Kurzer Augenschein, dann die Papiere angesehen (anders als der oben!), dann die technisch wichtig Sachen wie Lenkkopflager, Lichter - Standlicht? ach so das ist ja gar keins, OK - Bremsen usw.

Dann, Fahren Sie das Moped warm, damit wir messen koennen. Auch OK.

Stempelt erteilt - ohne Beanstandungen.

Wohlgemerkt, dasselbe Motorrad eine Woche spaeter.

Ein krasseres Beispiel fuer Behoerdenwillkuer beim TüV kann man sich nicht denken.

a 1978 Ducati 900SS

2008-02-16T08:26:00.001-08:00

And now for something completely different.

Two years ago, we rebuilt a 1978 Ducati 900SS belonging to a friend of mine. He bought it from the first owner in 1982 and has had it ever since. But after 25 years, it was in need of serious work.

We decided to rebuild the cylinder heads, making the necessary modifications for lead-free gasoline. The valve seats of the vertical cylinder were shot anyway. When we dismantled the engine, the valve seat rings could be turned easily with a Seegerring pliers. No wonder that cylinder had no compression.

New seat rings were made from scratch of sinter material. New valve guides were also made of sinter bronze and of course new valves were fitted. The seats for the seat rings had to be milled square and clean to accept the new rings.

The carbs were cleaned and all seals and the accelerator pump membranes renewed. Otherwise, the engine was in good condition.

I decided that it would be a good idea to make a new wiring harness since the owner had more than once been stranded with an empty battery for no apperent reason. Italian electrics are questionable at best. Using the Silenthektik automatic fuse box and SilentHektik controller, I made a new harness. Only the ignition remained original. Although there is no starter, I chose to fit a Hawker SBS8 battery. It is almost indestructable, needs no care at all and fits the bracket perfectly.

The owner had fit an aluminum tank from Sauer shortly after he bought it, one of the first Sauer made.

The original owner had already done away with the original cockpit, fitting a DIY stainless steel item, clumsy and not nice. The original item was fiberglass and cannot be had new for whatever price. Only poorly made copies are to be had now. I milled a new one following the original form out of aluminum which was then anodized black. The owner had replaced the original Smiths instruments with Veglia, utilizing an original and coveted "Competizione" tach like those found on all 50ies and 60ies Italian racing motorcycles. Of course these were kept. The owner does preserve the original Smiths clocks as well.

This 1978 900SS is something of an oddity; it is one of the first original left side gear changes but it has original Borrani wire wheels. Officially, the left changers were not delivered with wire wheels and those few made prior to 78 for the US market with a left side change were right side shifters with a clumsy linkage from the left to the right through the swingarm axle.

Also this one appears to have always been red but there never was officially a red Ducati at this time. It is very probable that this one was specially built to order by the German importer.

All mechanical details were seen to, the shift and brake linkages repaired and bushed.

To complete things off, we mounted a new chainset, new Bridgestone BT45 tires and new Ikon struts. these are the successors of the world famous Koni struts.

The best part is saved for the end: the owner wishes to sell the bike unto responsible hands.

Any serious inquiries whould be directed directly to me be email:

bill@william-jurgenson.com

The bike is stored in my shop, is licensed and can be, weather permitting, test ridden any time.

update

2008-02-11T01:54:00.001-08:00

Monday,
not much to update. The bike has still not been to inspection and so I haven't been able to register it yet.
But the weather is greatly improved and so I rolled it out into the sun last Saturday to take a photo or two:

It is running and appears to be ready for the inspection, so I need to borrow a trailer (I no longer have the van) and tow it over to Karlsruhe to Heinz Weber for that.

I am still not satified with the carburator settings, but my experience tells me not to expect too much with the quiet can installed. After getting the stamp, the can will be replaced with the other Remus which, while much louder also has much less backpressure and is easier to jet.

I also recently fitted a pair of PVM 3-spoke aluminum wheels to a Skorpion Tour for a friend.

Both brake calipers as well as the front pump were changed to Brembo units. The front rotor is a Spiegler with cast iron ring.

Besides fitting the much better wheels, I also installed a lightened flywheel/freewheel assembly.

all for now.

Loctite data

2008-01-25T02:32:00.001-08:00

Since nothing is less understood and gets more misused than Loctite, I have append this list of links to .pdfs on Loctite's data base. I have marked the important ones for us in red, the ones I find indespensible in green.

Gasketing

Loctite 504 gasket eliminator

Loctite 5926 Blue silicone!!!!!

Loctite 5920 hi temp copper

Loctite 587 blue paste

Loctite 548 stick

Loctite 514 eliminator - hard hi temp

Loctite 5999 to 150º

Loctite 598 black xtremeflex to 260º

Loctite 5970 timing covers and oil sumps

Loctite 597 bonds to oily surfaces

Loctite 5927 to 315º!!!

Fastening

Loctite 672 for bearings

LoctiteTight

Loctite 085

Threading

Loctite 089 - interesting

Loctite 088

Loctite 086 mid strength

Loctite 085 medium and bearing seats

Loctite 084 normal usage

Loctite 2050 lubricates!

Loctite 2045 automotive

Loctite 205

Loctite 2015 lubricates & hi temps

Loctite 259 normal application

Loctite 348 stick

Loctite 245 normal usage

Loctite 242 THE normal Loctite

Loctite 2432 -for titanium

Loctite 241 like 243

Loctite 220 low strength

Loctite 274 - medium; hand tools

Loctite 2701!! permanent

Loctite 268 hi strength stick

Loctite 589 locking and sealing

Loctite 279 locking & bonding

basics

2008-01-24T09:16:00.000-08:00

Now that I am getting old and pedantic, let me make a few basic comments.

Get the best tools you can afford. They are the cheapest in the long run.

In Europe, these are in the order of my preference:

Stahlwille

Hazet

Gedore and Dowidat

Facom
Bahco

In the States, I would say Snapon and then Craftsman. Because I have various antique machines including English, I also have a basic set of Metrinch tools.

The best side cutters I have ever seen or used were from Utica. They no longer exist, but you do see the tools on eBay.

Use box wrenches wherever possible. Don't use offset wrenches when you can avoid it. They slip off too easily and tend to ruin the nut or bolt head. In that, they are not much better than open end wrenches.

My main rachet drive is a Stahlwille 3/8". I use 1/2 sockets for the impact wrench and of course 1/4" sockets for smaller things and hard-to-get-to places.

Two tools I find indispensible now that I have them are T-handle socket drivers. I cannot recommend these highly enough.

Likewise, T-handle Allen drivers are very handy.

Facom also offers them and I prefer these.

Do not use zinc-plated screws because the galvanic treatment weakens the alloy. Try to use 10.9 or better 12,8 grade bolts, especially for Allen-head screws and bolts. That will alleviate a lot of headaches later.

another pet peeve: don't ever use helical spring lock washers.

Where ever possible, use so-called Schnorr safety washers.

These are serrated disc springs. Although they look harmless, they actually hold much better than other designs and do not ruin the part or the bolt. Use them only once!

Try not to use Loctite 270. Use a torque wrench and the proper torque and above all, use a suitable grease on the threads or you don't even have to bother with the torque wrench.

Here is table of torques to download and paste in the tool box.

will be continued...

balancer shaft and myths

2007-12-09T09:21:00.000-08:00

Some simplified facts about counterbalancers and singles

Unlike a crank with 180º or 120º throws which can be balanced, the single cannot be balanced. Or rather it can of course, but both possibilities are not functional.

1) make the counterweight of the throw heavy enough to balance the crankpin, disregarding the conrod and piston. This indeed balances the crank, but leaves the conrod/piston assembly entirely uncompensated. You have reciprocating mass: both coupled parts going up and down in the barrel. This generates free mass forces of the first order and these cannot be compensated for in a single. In a 180º twin like a 2-stroke or the venerable CB72 or the MZ1000 or in a normal 4 cylinder you have this: one (2) piston going up while the other(s) is going down. The Ducati Super Mono was built from a 888 engine and retained the conrod of the vertical cylinder connected to another rod with counterweight to emulate the missing piston so the engine acted like a 2 cylinder. The new 850 BMW, a true parallel twin (360º crank), has exactly the same system, tho they act like they invented it. Typical BMW. It should be obvious that a 360º parallel twin acts just like a single as far as balance is concerned unless a third(fourth) linear mass of the same size going in the opposite direction is used. This is termed a 0% factor.

2)Compensate the mass of the conrod assembly with the counterweight of the crank. This will of course balance the 1st order mass forces at 360º and 180º but it creates havoc with those of the 2nd and third orders at 90º and 270º because the mass of the crank counter weight is much too large for the crank itself. The engine will vibrate crosswise, at right angles to the cylinder, and probably take itself apart literally. This is termed a 100% factor.
Too little factor and the conrod/piston make the motor/bike jump up and down, too much and it moves front to back. Inclining the cylinder reduces these effects with regards to the axes of a bike, but does not compensate them. Flat singles like the old Guzzi, Aermacchi, or Motobi can thus get away with less and they seem as far as the bike is concerned not to vibrate as much as a contemporary Ducati or Morini with their vertical cylinders.

Using a separate heavy flywheel also goes a long way towards smoothing out. It is completely balanced in itself and its very high 3rd order mass force dominates the smaller 1st and 2nd forces. The engine will idle at extremely low rpm and it is easy to kick start. For your own experiment - maybe you did this in high school science class - take a two bicycle wheels, either of different diameters or different masses, say a 26" wheel from a mountain bike and an 18" from your kid's bike and spin them in your hands. You will feel the difference in momentum. This is the main reason for having the crankshaft crosswise in a bike and not lengthwise, BTW. At right angles to the axis of the bike, the crank stabilizes the bike and acceleration has no effect on the stability.
Obviously, though, the heavy flywheel with its momentum also makes the engine slow to respond. Gives it those qualities that would make it a thumper - which the XTZ is definitely(!!) NOT and indeed no modern short-stroke single is.

So, singles are "balanced" statically by compensating only a percentage of the conrod assembly mass. One speaks of a 50% factor or a different one somewhere between 40 and 60%. Any talk about fine balancing or dynamically balancing a one cylinder crank is nonsense. It is just conning the customer. It is done statically with a very very good scale and lots of patience and experience. NB: if you put a Wiseco, JE or other aftermarket piston in your engine, weigh it first. It must be EXACTLY like the OEM piston or you will have to "rebalance" the crank. If it is heavier, remove material carefully inside by drilling until it has the proper weight. If it is too light you are in trouble. I would send it back unless you are seriously into machining.

Very simplified: the resonance curve of the crank assembly is countered by that of the balancer. The counterbalancer also has a curve, but unlike like the crank; the height of the peaks are dependent only on the actual mass of the weight(s) on the balancershaft: they stay the same all the time, while the peaks for the crank get larger due mostly to the linear movement of the piston. Since the shaft in our case is offset from the crank by 180º, its peaks fall in the valleys of the crank diagram. At a certian rpm, both are "in balance." Above this point and the effect of the balancer is less since the peaks of the crank get larger; below this rpm and the motor peaks are smaller than the constant of the balancer. A heavy balancer increases the effect, a lighter one lessens it. The balancer AND the crank balancing are then calculated for a certian rpm range, one that is thought to be critical for the the use of the engine/vehicle and one - much more important today - that is exactly within the emissions rating specs. This is for the XTZ (3YF) engine between 4 and 5000 rpm. It is important to remember that the maximum effect of the balancer can only be at the specified speed. Below that and above that the effect becomes less and less. At the extremes, the engine actually vibrates more due to the balancer than it would without it. this is the case at idle for instance, but also above 6500. The 4000rpm range is the engine speed for legal driving and the speed range projected for the minimum emissions, both CO2 and noise.

If your riding habits and use hover in this area, there is no reason to think of any modifications to the XTZ engine, let alone removing the counter balancer. In this context, there is no point in replacing the OEM L&W exhaust system of the Skorpion because it cannot be bettered. The same cannot be said of the SZR exhaust at all. All the alternatives are just louder and possibly lighter. Most, in particular the BSM, return less performance than the OEM part. Less that is, until you change a lot of other things, too.

If you want/need performance, there is all the reason in the world to remove the balancer and lighten the flywheel/starter freewheel assembly. Above 6500, a balancer-less engine with lightened flywheel assembly actually vibrates less than the stock engine. Above 8000 it is very smooth, actually. It is also much better at idle, too. If the tuning is relatively mild, i.e. does not have a really wild cam, tickover can be turned down as far a 800rpm with a warm engine, a speed at which the stock engine will not run at all. Not that there is any virtue in this, but it is nice as a demonstration.
Lightening the crank and rebalancing the complete assembly with conrod and piston is the next step since it reduces vibration, reduces small end wear and also reduces the mass that must be accelerated. This is a lot of work and takes hands-on experience. This is the time to rebuild that crank with a Carillo (or other suitable choice, which), since it is heavier than the stock item, needs compensation. For street use and performance levels up to 60hp, you do not need a Carillo.
My racing engine actually vibrates far less than the stock engine at racing speeds and responds to the twist grip like a 2-stroke. Not having a flywheel of any kind, it will not idle below 2000. What for? This is a racing engine. The Bimota won't idle below 3000.
This is getting too long. Sorry.

Bill

http://www.zabernet.de/bill/tuning.html

2007-12-01T08:01:00.000-08:00

Other things than MZs.

I got back into motocycling 1986 after 20 years pause by way of veterans. I had always wanted a Aermacchi 250cc Ala Verde or a 250 Parilla. After some questioning around, I found one of the top Aermacchi experts and collectors in Germany and, after calling him, went there to perhaps buy one to restore. Once there, he showed me the bike in question but also asked why that one in particular? And if I wouldn't like something much more collectable and rare. He then showed me both of his F.B.Mondial 200SS, one of which he was willing to part with. I bought this, loaded it into the van and drove home, my 6 year old son sitting on the bike in the back, "driving." Two years later I found another, quite by chance and bought it as well.
I restored the good one, went through vehicle inspection and registration and, 199o with only a few hours on the rebuilt bike, got shot down in town by a Porsche driver who was not paying attention.
The bike was a insurance write-off. Using the other bike - it was exactly 6 months younger than the wreck, both 1954 - for parts, the bike was rebuilt. You can read a bit about this here.

After recuperating for the accident, I bought a 1974 Benelli/Motobi 250SS, in decent condition and ready to ride. This was really a good bike, very light, very quick, but very fragile, too. 10000km is really good for that engine. I rebuilt that engine twice, each time learning more about its quirks and also finding more people who really knew about them. The last rebuild was rock solid and hot as well, putting out 32hp in race trim. It was used in a Zanzani racing Motobi by the man who did the really important stuff. Back in my street bike, it still retained about 26hp and weighing only 105kgs, it was quick. I was the scourge of the back woods; the bike was infamous as far away as Frankfurt. When I bought the MZ, I sold the Motobi to a one-time race rider who, despite his age, terrorizes the weekend would-be Rossis on his house stretch between Nesselwang and Oberjoch, a one time hill climb route in the alps with 122 curves.

Through my machine-shop work with MZs and racing, I came into contact with other "nuts."
This brought me Pierre's 1978 Laverda Jota, a 1000cc 180º crank three cylinder with 1200cc cylinderblock and head that had always been used as a racer. It still had its 1978 magnesium wheels installed. Due to regulations but also in the interest of safety, I installed aluminum wheels. I also fitted a very small rear brake instead of the original monster thing along with much farther foward in-house made rearsets, raised the seat 60mm, clipons with less reach... A SilentHektik constant-loss battery ignition was fitted on a custom-made side plate, doing away with the flywheel entirely. The starter was long gone. At the rear, new Ikon (Koni) struts were fitted. At the front, I made a partly successful attempt at getting the fork to actually work. I can live with it now. The bike weight, thanks to hacksaw, angle grinder, lots of aluminum and some titanium, was brought down to 192kgs. The original street-legal weight was upwards of 240kgs. From its earlier racing days, it already had a lighter crankshaft, high compression pistons, hotter cams, larger carbs, a works 3-1 exhaustwith a mean megaphone. The bike is pretty quick with its 100hp and torque like a traktor. Missed a shift? so what. Don't bother.
This is Pierre's bike, not mine and I normally do not ride it, but I have, mostly for testing and can testify that is or can be daunting.

Through other aquaintances at the tracks, I became friends with Karl Klumpp, a really good mechanic and Aprilia dealer, who also sponsers two young and promising Aprilia cup riders and takes care of their bikes. He had been storing a Bimota DB1SR ever since it was retired from serious BOT racing around 1990. I pestered him that it was real shame that beautiful and rare bike was just sitting around, collecting dust and deteriorating. Two years ago, he decided I was right and gave me the beauty on loan, first to put back in perfect order and then to use as I see fit at my own responsibility. During the winter, it resides in his showroom.

I had to fit a new 17" Marvic magnesium front wheel in place of the 3.75/16" Campagnolo and for this it was necessary to machine my own brake rotor hubs to fit the calipers. I did not want to change anything on the machine if possible. The rear wheel was already a 17" Marvic; the 18" original wheel had been replaced during its active racing days. Back then, 16" fronts were popular and racing tires were to be had, unlike today.
That is one serious NCR works megaphone. This bike is LOUD. At one event, we tried to measure it and could not: out of range! that means over 130db. Otherwise it has the the complete NCR treatment: cams so wild the engine will not run below 3000 rpm, BIG smooth bore 41mm carbs without accelerator pump or choke, no flywheel. From the performance, we estimate 100hp, uncannily smooth power from 3500 to the limiter at 9000. It weighs in at 135kgs! ready to race and is smaller than a modern 125cc bike. Handling is otherworldly, and performance is good enough to cope with much more modern machinery. Sure wish it were mine!

I have entered it at a very few chosen events, none serious racing, but serious events in their own right, such as the Lueckendorf hill climb, the oldest hill climb event in Germany, started 1923.

Apart from the Mondial 200SS talked about above, I also have a 1962 F.B.Mondial SSV4, 50cc 2-stroke weighing only 56kgs. I have the exceedingly rare Walter Villa tuned version, unrestored and running. I found this one under a tarp at a Fiat shop in a small town near Bassano del Grappa in northern Italy while we were looking for Fiat parts. I bought it immediately. The photo show me with the legendary Ernst Leverkus - "Klacks" - and at the far right Dr. Paul Simsa. The person bending over the NSU(?) is Karl Reese, I think.

As if that wasn't enough - is it ever? - I also have a 1954 BSA A7, a 500cc parallel twin which is registered and licensed and not restored. It is in ±1970 café racer condition the way I got it and the way it is going to be left. I have been using this since registration this year on an almost daily basis.
What can I say? How does it compare?

The Italians in general and the Mondial in particular are absolutely beautiful on paper, at the drawing board. Often though, the actual manufacturing quality leaves to be desired. To be fair, this must be expected of companies like Mondial or Bimota who made very small series of only a few in most cases, some models changing almost from machine to machine. They work and work well because of the flawless design and where they need help, it is in the remanufacture of the parts, not in redesigning.
British iron is something other. The engine design is very often clumsy at best, occasionally breathtakingly bad, but the manufacturing quality is so good that it works in spite of itself. A typically scathing comment:' as long as it looses oil, you know there's oil in it.'

In both cases, the electrics are a book with 7 seals. Lucas is not called the "Prince of Darkness" for nothing and until very recently Italian electrics were even worse. The MZ Skorpion is a case in point with its CEV electrics.

In both cases, frame design is usually very good and also usually well made. Italians tend to be underdesigned, British over dimensioned.The BSA above weighs 190kgs, just like the Laverda or the MZ Skorpion ready to go, but it only has 28hp. Thankfully, 'cause the 8" SLS drum brake can hardly cope with that. The Motobi with 26hp had 1-finger braking despite drums and the Mondial brakes almost as well.

One could say the Italians work because of the design inspite of the quality shortcomings, the British work inspite of the design because of the high quality. Both the BSA and the Mondial 200SS are 1954.

December 1st, 2007

2007-12-01T01:28:00.000-08:00

update, December 1st,

the "castration" of my racer is coming along. The bike is starting to look like something street legal again. As I reported, the blue Tour has been dismantled for good. I intend to use the frame for a "pet project:" putting the 850, TRX engine in the Skorpion frame. I hope to find out this winter if this is feasible. Meantime, the parts have gone to the shelves - except for Remus Cup exhaust which replaces the 128db Barker 2-2 system and the wiring harness, which I have installed, slightly modified.

The Tail light is brand new, a Hella , probably originally for a some truck or traktor. It is almost beautiful in its old-fashionedness, entirely of metal with threaded inserts to mount. Inside, with two separate bulbs , a metal horizontal separator, and sturdy all-metal connectors.
The headlight is the original from my red Sport which I had replaced with a much lighter one from a TRX. I will probably fall apart here as well, but for the moment, I am using this one. These headlights with their two separate H1 lamps aren't renowned for their durability, so it is just a question of time. The FZR/TRX headlight has a single H4 lamp.

Anyway, the harness is installed and everything is working: lights, horn, blinkers, starter relay, etc. etc. It utilizes, as in the blue bike and other bikes I have restored, the SilentHektik fuse box. I have installed a new ingnition lock on the side of the subframe under the seat, not unlike a Harley or Buell but on the right side. This way there is no unswitched +12v line anywhere except for the 6" from the battery connection to the ignition switch and the wire directly to the thermoswitch for the fan and this one has an inline fuse.

The ignition switch turns on the SilentHektik fuse box which is also only about 6" away. There is another reason, too, for this solution: my CNC billet triple tree has no provision for a lock.
The kill switch on the right twist grip switches the built-in relay of the SilentHektik fusebox to supply + directly to the CDI and coil.

Apart from many small details yet to be done, I still have one larger "detail" to attend to. This is my race engine. It has a roller timing chain, not the stock Borg-Warner silent chain. The crankshaft sprocket from Slipstream shown at the right, does not fit behind the flywheel/starter freewheel assembly. The racer had a SilentHektik constant-loss battery ignition and no flywheel at all. There was no problem.
I have to make a new sprocket , matching the original par but for the rollerchain myself. Theo is going to help me get it right. Making gears is a bit more complicated than turning a wheel spacer.

The new gear is finished:
It is made of 1.2714 and nitrided to a depth of ±0.3mm.

Here you see it in place, the engine ready to close up - finally.

So, in the meantime the bike is completed. I have not run it yet, but it shouldn't be to much of a problem; it ran in the spring with the racing ignition. Anyway, with the snow and above all loads of salt on the road, I am not about to take it out for a test ride.

Today I bought a can of coolant and mixed a new batch 2:1 and filled the radiator. Didn't start up right away, I fouled the plug with either too much accelerator pump or too much choke. But then it did catch. I had to keep it alive with the throttle; no idle when cold and very little when warm. That is how I had it as a racer; the idle jets are too small but the next sizes are missing in my assortment. I had previously checked this and reduced the main jets to 130 and 135 from 140 and 145. I now have an air filter after all and more backpressure from a muffler. I will need at least size 30 idle jets. Once hand warm, it did settle into something like an idle at less than 2000rpm. Despite, now having a flywheel and starter freewheel, albeit my lightened version, it is still one mean powerplant. Can't wait (but will have to!) to test ride it now in street trim and get it on a scale...
In race trim, it weighed in at 125kg ready to race. I hope I have been able to keep it under 140kg. We'll see.

2007-11-30T21:09:00.000-08:00

Bill's Skorpions....

1990 was the first showing of the award-winning Seymour Powell prototype with Rotax motor. Seeing it, I said this is the bike! I kept an eye on developments, meanwhile riding my 1974 Benelli/Motobi 2500SS. A late model with 5 speed trans. The engine - goes almost without saying with me - was heavily modified and had seen use in a Zanzani racing frame. In street-legal trim it still had 26hp and the bike weighed all of 105kg, ready to go.

Here in my home town of Lauffen, one of the oldest west German MZ dealers, Probst, has or rather had his shop. Had because, due to the turmoils caused by Kourus, they eventually got so fed up with MZ that they stopped dealing with them. 1994, they had the first two Skorpions in the Stuttart area, a yellow Sport and a blue Tour. I test drove both and bought the Tour straight away as the first Skorpion sold in the Stuttgart area. It was so early in production, that the modifications (cut off corner of exhaust can, longer vent hose, etc) were not yet done. I had the can modified at L&W in Lorch - they still existed in that form and they did it for nothing! Until September this year, I have been using it ever since, summer and winter.

Within the first year, I had exchanged the front springs for progressive Technoflex (now Wilbers) as my mechanic advised and the clipons for welded aluminum Harris racing clipons. Not two years, and I had to replace the strut because the spot-welded nose for the spring base tore out, emtpying the oil. Again the mechanic advised me against simply replacing the Bilstein, on the basis that a really good strut from Wilbers would be only 150DM more expensive. I ordered one with adjustable length to lift the tail. The fork had long since been stuck thru as far as possible. After replacing the tach twice, I replaced the entire unit with a DET 100 which I highly recommend.

Sooner or later, I replaced the muffler with a BSM Future, which, while prettier and lighter and louder, was also not long lived. The insides vibrated loose, the baffle slid forward, closing the pipe entrance to the can. I had wondered why the bike seemed to be getting quieter! No way to fix it, so I bought a BOS for a Kawa ZX750R; the three hole pattern is the same as the BSM, and this one is still going strong, even after several groundings. I no longer use it, however.

Somewhere around 35000km, the gear driving the counterbalancer sheared off the Woodruff key in the crank. EGU rebuilt the crank with the original conrod; the balancer went to the dustbin after due deliberation. I have not regretted throwing it out!
That was basically the condition the bike was in for the very first MZ Skorpion Forum meeting in 2002.

I had added a steering damper. Otherwise, the crappy Grimeca wheels and brakes were still in service. And the battle scares on the can from Hockenheim are clearly visible.

2003, I bought my green Sport from Heinz Weber, who basically built it.
It was built from scratch from a new Skorpion Sport and a new Yamaha SZR; the frame is the first prototype frame for the Replica from MZ development which was eventually rejected as being too light and flimsy. Actually, there was almost nothing from the new Sport used: swingarm, strut, gas tank and fairing, seatframe which was heavily modified, airbox, radiator, front frame brace, exhaust system tho the can was also highly modified by L&W. Motor, wheels, fork and brakes , wiring harness and instruments and headlight, all from the Yamaha. Rearsets homemade. This bike weighed 165kg ready to go.

After some encouraging outings on the track and more than one spill caused by the exhaust system grounding, I decided to use the green one only on the race track. That is when I started modifying engines, this one first, then the blue one, then the red one - more later. This one already had a Carillo conrod, a J&E 102mm 12:1 piston, a Megacycle 280/2 cam, and new one-off porkchop style crank. I rid it of its balancer, putting my balancer dummy and did some porting.

Next came the Bikeworx kit with Mikuni TM42. Then I had the idea of lightening the the flywheel/starter freewheel assembly. This was not used in this engine very long, however, because I threw out the starter and flywheel entirely, going to a magneto ignition. The lightened flywheel assembly, which I offer, went into the blue bike. The TM42 was replaced by a dual TM38-65 mounted on 2" long intakes and the magneto replaced by a constant-loss ignition system which made starting infinitely easier. The Megacycle 280/2 cam was replaced by a full-race cam with Kibblewhite valve springs, the ports reworked some more and a Barker 2-2 exhaust system mounted.

2003, I also bought a 1995 red Sport. Both it and the blue bike got SZR wheels and Brembo brakes, the red one a Mikuni TM34-65 carburator and a 8400rpm modified CDI like I was using generally. The red bike got the exhaust from the racer after I bought the Barker 2-2 racing system. It also got the rearsets from the racer for which I had made new billet CNC milled 7075 rearsets, both for it and the blue bike. The blue bike got the seat frame and seat from the racer since I had also bought a Barker aluminum subframe and a Pferrer seat. In the end, the blue bike also had the TM42 since the racer had gotten the TM38-65.

When my son started to ride, I reduced the red bike to the legal 35hp.
getting confused?

These are the MZs:

1) the 1994 blue Tour which I have now dismantled; it had over 80 000km:
SZR Wheels, Brembo brakes, one-off harness with Silenthektik box, Technoflex progressive springs, Sachs fully adjustable strut with White Power Spring (Replica), Gilles clipons, 101mm Wiseco piston, Megacycle 280/2 cam, no balancer, lightened flywheel assembly, SZR cluster, reversed shift pattern, TM 34/65 flatslides, light porting, Remus Cup exhaust system (5 mm larger headers and much better ungroundable routing), seatframe and one-off kevlar/glass seat from the green bike, 8400 CD, DET 100 Instrument. Dyno tested 59hp at the rear wheel, 150kg. 15/43 with DID 520 ERV chain. In this bike, ALL of the screws except the three long M6 bolts at the timing chain and the cylinderhead bolts have been replaced with either titanium or aluminum as necessary. That includes all the parts of the strut linkage; the dogbones are aluminum. The swingarm axle is also titanium.

2) The 1995 red Sport, which I then sold, or rather traded for the Yamaha SZR I still have: as above, Brembo SZR wheels and Brembo brakes, the handmade rearsets from the green bike, TM34/65 flatslides, 8400rpm CDI, Tommaselli forged clipons, lighter headlight from a TRX, Lighted seatframe and fairing frame, Mito mirrors, BSM Future exhaust, 15/43 rear sprocketwith DID 520ERV chain. DET 100 instrument. Aluminum screws were used here to a certain extent as well. Otherwise this bike was completely stock. It ran a verified 190kmh with the short ratio. I went from Milan to Turin at a nearly constant 180kmh. That's over 200km expressway at 8000rpm. Didn't break then - or later.

3) The Green bike was strictly for racing: 125kg race ready .

4 stroke, 5 Valve: 700ccm
weight of race-ready engine with carbs and all fasteners wired:: 40kg .

Special welded"Porkchop" crank. no counterbalancer, Carillo rod, JE 102mm 12:1 piston, Megacycle full-race cam, Slipstream rollerchain conversion, Kibblewhite springs and titanium retainers, titanium locknuts, ported head, Mikuni TM38/65, Barker 2 in 2 racing exhaust, Barker CNC sideplate, SilentHektik costant loss battery ignition, Yamaha works cluster. Of course, here, too, all screws, bolts and nuts are either titanium or aluminum just as above. triple tree is one-off CNC milled billet AL7075, SZR fork reworked by Wilbers, Wilbers fully adjustable strut, Barker aluminum set frame. Marvic magnesium wheels with Bridgestone slicks, ABM CNC billet front caliper and billet radial pump. Mecdine speed shifter. Just shy of 80hp at the rear wheel.

That was up till this year. I decided to stop racing due to my age and build the racer back to something approaching street-legal. It will have Brembo TZ250R 3MA wheels instead of the Marvics which cannot be registered in Germany - no mag wheels can. It will also have the Remus Cup exhaust shown above on the blue bike. Of course it will have the lightened flywheel assembly and a starter again and I will need to make a new harness for it. But inside, the engine will remain untouched. I hope to keep the aluminum subframe and Pferrer seat but the subframe needs considerable revamping and welding for street use. Of course the ABM brake will be retained. I hope I can keep the weight down to 135kgs and the hp still around 65, maybe even 70.

Lauffen in October, 2007
http://www.zabernet.de/bill/tuning.html

riding position

2007-11-17T08:23:00.000-08:00

After repeatedly reading a lot of BS on position and numbed hands and aching necks, allow me to make few observations on riding position.

But first a short account to start with: yesterday, I drove the 30th anniversary of a good friend's organbuilding shop with my blue Skorpion. Over 300km, coming back the next day, 300+km again plus 50-60km after removing the tank topbag. In general, my Toy is judged as having a radical racing setup and not at all good for riding any distance at all. The missing counterbalancer also contributes to this appraisal. OK, 300km ain't that far but Siegen, the town where I went, is just not further away.

Whatever

no numbed hands
no aching wrists
no aching knees, altho my right knee was demolished beyond repair skiing decades ago
no stiff neck
and all this despite the would-be radically uncomfortable position and the vibrations.
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First, a simple test of you riding position:
Put the bike on its centerstand if available, a paddock stand or have someone hold it; seat yourself as if you were riding. Now let go of the bars, that is, open your hands but leave them on the grips, do not change anything else. Now attempt to stand up on the pegs. Can you do this? If so, your position is basically correct. If not - you will most probably fall forward - your pegs are too far back. Perhaps the bars are too far forward, as well, tho this is not probable with the Skorpion. More probably, the bars are too wide which has a similar effect. The stock clipons of the Skorpion Sport are too wide.

The point is this: you must be able to put your body weight on the balls of your feet. This is necessary both for a relaxed position and secure control. I repeat: the balls of your feet, NOT the INSTEPS, belong on the pegs, regardless of what you may have been told at drivers ed. Part of your weight should be on the pegs at all times, not on the seat. As with a bicycle, the seat is between your thighs, not just under your backside. More or less loose between your thighs - while driving of course.

Driving straight ahead, the weight should be distributed equally between both feet. This way you can immediately react to very bad road conditions, the bike can tip for and aft around the axis of the pegs/your feet without pounding on your back or wrists. In curves, the weight should be on the outside peg. It should be obvious that this is only possible when the pegs are far enough forward. For the Skorpion Tour and Traveller, the brackets are fine, for the Sport, the front hole is already almost too far back. For a comparison, drive to you local friendly Yamaha dealer and test-sit (test drive even better) an R6. You'll be amazed how far forward you sit, how close to the bars, how far forward the pegs are and this on a so-called super sports bike.

Once you have sorted the position to pass the test above, you should be able to drive longer distances without aching wrists.
Mounting a superbike bars, so popular at the moment, is in reality a move in the wrong direction because the higher, wider bars move you weight too far back onto your backend . The very upright position also makes the front end very light and this tends to make it nervous, quite apart from steering geometry. Unweighting the seat to let the bike take care of itself is also much more strenuous unless you have thighs like a professional skier. In most cases, riders on such setups are taken for a ride; the bike controls them and not the other way around. Normally, the centrifugal forces of the wheels and to a lesser degree the crank if crosswise mounted stabilize the bike. Misbehavior is brought into the constellation rider/bike mostly by the rider himself. He must learn to let the bike have its way. It has not always been this way. Old weak or poorly designed frames definitely needed to kept under control by clamping the knees on the tanksides, Long reaches, far back rearsets, all that is part and parcel of a bygone era. Modern bikes and even more modern tires worthy of the name not only do not need this, they react allergically to it.

Once again, the pegs must be positioned under the body and between steering head and seat so that a triangle is formed in which the center of gravity(CG) is exactly on the pegs, on the balls of your feet. If the pegs are too far back, the triangle tips forward, moving you weight away from your legs and onto your wrists. That is what the test I started with is all about.

It is a simple as that.

It is entirely possible that the stock settings cannot be made to fit. Very tall people should raise the tail without sticking the fork through, i.e.raise the entire bike, perhaps even put the clipons under the triple tree so that the fork can be pulled out even more. Raising the tail to match retains the original geometry while raising the entire bike. The higher CG requires less lean so pegs can be placed lower safely. Other brackets may be necessary to get the pegs low enough and far enough forward to suit.
When the best position is found, set the shift lever so that you can shift with your big toe without really moving your foot (remember: balls on the pegs). The brake is similar, altho on modern bikes, the rear brake is only of limited usefulness and should never be able to lock up the rear wheel easily. That can be very dangerous indeed. Do not normally use the rear brake at speed, regardless of what you have been told. Racers use it only to quiet an unruly bike (shimmy or kickback which are not the same thing) by a quick tip on the pedal. And of course they also use it to steer the rear wheel, along with the twist grip. They do not use it as a rule for actual braking. Get out of the habit of using it for anything beyond coasting up to a traffic light. Or quieting shimmy while on the expressway with your overloaded vacation trip package.

One more point: I counsel everyone to change to first gear up and simply mount the shift lever from a Yamaha XT reversed directly on the shaft. Just about everyone who has tried my bikes or let himself get talked into it, was almost immediately convinced and exclaimed, 'why on earth is it standard with 1st gear down?'

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Knee down and hang off: it is a question of riding style and bike and above all seating position. You absolutely have to have your body weight on the pegs to ride hang-off with any control.
But it is also a question of tire width. A wider rear tire needs more hang-off than a narrow one. A low center of gravity also needs more hang-off. That is why the present 2005 RC-211 has a higher CG than the 2004. And also one reason why I raised my racer; 40mm for the bike itself with longer Wilber strut and shorter aluminum dogbones and another 40mm the seat alone. It is now quite tall. I still have to pull my knee back up in hard cornering to get it out of the way. Getting it on the ground is no problem at all.
Hang-off requires some practice and definitely requires some competent instruction to do correctly and it requires fitness. Race riding is hard work, contrary to popular belief. It does not require any particular bravery or abandon.
Do not do this in traffic on open roads.