Bill's Skorpions....

The MuZs keep on coming. But hey thats what this blog is about. :-) Those great German single cylinder bikes. To prove how good they are and how great they can be made, Bill from Germany would like to show and tell us about his three MuZs.

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 - 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 Stuttagart area. It was so early in production, that the modifications (cut off corner of exhaust can, longer vent hose) 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 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.

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 patern is the same as the BSM, and this one is still going strong, even after several groundings. I do not 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 regreted 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 a 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. So this one got a Carillo conrod, a J&E 102mm 12:1 piston, a Megacycle 280/2 cam, porting, and new one-off porkchop style crank and was rid of its balancer.

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, because I threw out the starter and flywheel entirely going to a magneto ignition. The lightened flywheel assembly went into the blue bike.

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 in both other bikes. The red bike got the exhaust from the racer since I had decided to buy a 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 Pferrer seat. In the end, the blue bike also had the TM42 since the racer got a 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 (3mm 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, BSMFuture exhaust.







15/43 rearing with 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 Stage 4 cam, Slipstream rollerchain conversion Kibblewhite springs and titanium retainers with 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 billet milled 7075, 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 need 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

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