MZ/MuZ Riders

is it a good idea to use the SZR upsd instead of a MZ fork with
harder springs?
According to Herbert Nickmans, a former belgian MZ mono racer, the
original mz front suspension is not that bad at all. He told me he
has seen a lot UPSD's that couldn't match the Skorpion's front in
performance.

And he is right as I know from personal experience. The Paioli RSU fork
is much better than the USD used by Belgarda. chaning to the USD is not
plug and play, either. You must make and press a new stem into the
Yamaha triple tree (or make your own) to fit the Skorpion
steering head. When you go to that kind of trouble, you might just as
well take a really good fork with fitting triple tree and make a new
stem for that.
I have both a SZR and one of my three Skorpions has the USD fork as
well (check out my blog). I had that one reworked by Wilbers and it
does work but in the end, that cost more than a new Wilbers "Roma"
would have cost when all the persoanl time involved is considered. USD
forks have definite advantages of course, such as better guide bushing
situation and stiffness. Within the performance boundaries of the
Skorpion or most any single, it is not really necessary. Depending on
the purpose, I would definitely change the springs to either
progressive from Wilbers or White Power for street use with occasional
outings on the track or to purpose wound linear springs for racing.
These would have to made to order based on your weight, the bikes
weight etc. With the RSU you will have to experiment with oil viscosity
and air cavity size. As I remember, I settled at 150mm cavity height
and SAE 20 oil. Have to look for my data sheets, been quite a while
since I did anything with that fork. I now have only the SZR (progressive springs from WP) and the green
Skorpion, the one with the USD (linear springs from Wilbers.
Another possibility ist to get an early R6 fork. The first R6 had an
adjustable 41mm RSU fork which you can simply stick into the MZ triple
tree. If you are thinking purely of racing, this would also get you a
decent 3,5" front wheel and a much wider choice of tires including
decent slicks. Would also mean smaller dual rotors. Lots of advantages
but only for the racing circuit.
Dual 310 rotors are not good; far too heavy and far too powerful,
downright dangerous. And pointless as the single 310 rotor is more than
enough for anything a SOS bike could deliver. Again a but: get a really
good racing rotor (I prefer cast iron but since they are no longer made
very hard to get!) from Brembo, PVM, Disccatiati, or similar. A Brembo P34 oro caliper
goes without saying and best quality sinter racing brake pads. Again,
with the cast iron, I prefer Carbon Lorraine C55.
ABM has a CNC caliper with the 40mm spacing which
is otherwise like a Brembo radial caliper with 4 individual brake pads.
It is very good! I used in on my racer. It is not cheap and not
absolutely necessary.


Regardless of material, the rotor should be a true full floater which
most street rotors as not. The stock rotor from the SZR/TZR is not good
and also too heavy since the hub is stamped steel. The good ones have a
machined aluminum hub. In general, you can tell by looking if a Brembo
(or MP=Motor parts = Brembo) rotor is full floating: the usual OEM
rotors (Ducati, Aprilia, FZR, etc etc) have 10 floaters (or less) while the
racing variety has 12.
If the so-called floaters are riveted as in the Skorpion or Ducati
Monsters, don't bother with them at all.
They are not floating at all. Only those with real floaters retained by
circlips (Seeger rings) are floaters. The amount of side play can be
adjusted with calibrated washers (Passcheiben) available in 0,10mm
steps which you put under the the Circlip.
The assortment of rotors that fit the Brembo wheel is vast.
If you can offord it, a rotor from Braketech (Durbahn here is Europe). The reduction in weight
would be very good.
For you, the data is the important thing: 68 hole diameter, 80mm
bolting pattern diameter with 6 M8 bolts, 10mm offset. You may or may
not know that Brembo belongs to Yamaha (along with Oelins, Paioli,
Marchesini, MP which all belong to Brembo), so it is easy to look for
front rotors for FZR 1000, FZR 750 and OW1. Rear struts from the OW1
also fit the Skorpion as is so there are used Oelins occasionally in
ebay as well.
Very modern rotors are very different, however, with fewer floaters.
Much more expensive as well.

> b. The rear szr wheel has a very small rotor. How did you fix the
rear caliper to the swingarm to align to the rear rotor?

The SZR rotor is more than large enough; the MZ rotor is rediculously
large. Look at what I have in the 250kmh quick BIMOTA:


For the rear wheel, you need the Paioli brake plate (SZR/TZR/TZ reversed
cylinder) and caliper as well as the OEM Yamaha spacer between wheel
bearing. Leave the original 6202 bearings in the
wheel and use a 15mm axle with the Yamaha does. That way, you can use
all the OEM Yamaha parts: chainwheel carrier with bearing and spacer to
wheel bearing; wheel with both 6202 bearings and tube space inside and
oilseal ring right as well as spacer to the brake plate and brake plate
itself as is. Make a new axle out of 15mm stainless precision round
stock with M14 at both ends. Cut the thread on one end only as long as
the new nut is thick and force the nut onto the axle so that is is
fixed. The other end as usual but use a slotted nut and cotter key
which you will have to mark out, having tightened the wheel in the
first time.

Although I have never had trouble with the Skorpion with this, I had
big trouble more than once with the Yamaha, so I modified both as in
the photo.
Apart from the 15mm axle, you will need to make two simple collars to
reduce the chain tensioners to 15mm, slightly oversize and press in to
stay. For myself, I made the collar on the right side a loose fit in
the tensioner, but made is long enough to press fit into the brake
plate.

here at the left. You also need 15,5mm ID washers of course; I made
quite thick ones from stainless.
That way, The brake plate with spacer is attached to the swing arm and
does not fall off or get in the way when mounting the wheel. Far easier
and quicker that way. Of course you have to remove the caliper first
before removing the wheel but that is normal, anyway. Or should be. Cut
the right side of the rear fender short on the swing arm up to the
mounting screw so that the caliper bolt is not covered. Another of
those little things, the guys at MZ didn't pay attention to! The SZR is
FAR worse, though, since that front caliper bolt is shrouded by the
swingarm and cannot be undone at all. Talk about not thinking for two
cents! Race mechanics generally stick the axle from the brake caliper
side; with the stock SZR you have to stick it from the chain side so
you have room to fumple the brake plate with caliper onto the rotor
after the wheel is hanging on the axle, sticking the axle fully through
at last. Normal people bolt up the wheel first and then remount the
caliper. Many units, designed for long distance racing where tire and
brake pad changes (pit stops) are quick release or fold up
designs. No one fumbles a wheel into a premounted caliper, neither rear
nor front.
That stupid banana swingarm of the SZR is totally unecessary as it is; heavy,
pointless, in the way; its only justification was the exhaust of the
reversed cylinder 250 TZ engine. Japanese TZRs and all earlier TZs had
a straight swingarm which was also much lighter. Mounting the Belgarda
part to a Skorpion as quite a few have done is just plain stupid, good
for absolutely nothing. Bad for lots of things as you can see. The
Skorpion swing arm (actually Yamaha FZ600 complete with linkage) is
more than good enough and it is lighter, too. And the chain tensioners
are much better. Original Yamaha again.

In the carbu section. your defence on using the Mikuni TM34/65 was
impressive.
It needs an adaptor to fit on the 38 mm rubber on one side or another
34mm rubber to match the carburator, I guess.
How did you solve this?

When you buy the TM34-B65 from Topham the right carburator always has
a ring fitted over to match the rubber mount. Otherwise, of course,
making such a reduction ring is no big deal.

Herbert Nickmans told me that he bought a Ignitech electronic
ignition from you.
He also made it clear that after all these year of racing,
experimenting with the airbox size and length, he realized that the
ignition timing is also very important for such a large cylinder.
So, I understand that the Ignitech is definitely a must on the
"urgent option" list. For my MZ and my daughters SZR as well.

Definitely, at least for street use. The immediate advantage of the
Sparker is the ability to program a decent curve and this above all for
the lower half of the RPM band. Thus, the engine is much more drivable,
there is almost no chain lash and it is even possible with caution to
ride as low as 2000RPM in 5th rear. There is no advantage to running
that slow, but it shows how much better the curve can fit. At high RPM
as well but that is not "feelable." there is no reason to go beyound
32º BTDC, lots of reasons not to, and I keep to 29 as maximum. The
racing engine went only to 27º but that is also a question of valve
timing and overlap and RPM band actually being used. For a racing XTZ
engine that means effectively bewtween 6000 and 8500.
The Sparker also switches more quickly and delivers a better spark,
particularly when a really good coil like the SilentHektik Motocoil is
used and the dwell set to long.
As long as you keep the flywheel and pickup as is, the Sparker is the
best way to go in my opinion. I use it myself in both bikes and have
sold about 100 of them as well as other models for the SRX (true CDI)
and other bikes.
For really serious racing, though, there are other options which,
however, require the use of a different pickups or none at all. These
are only options if you dispense with the flywheel and starter
altogether. Only for all-out racing.
Spark plugs: don't waste money on racing plugs. Even the DENSO dealer
said that to me!
Use a plain old ordinary plug like a NGK DPR8EA. Try running a DPR7EA
and check how it looks. If it is not too white, use it. Don't worry
about burning a piston; this is not a racing 2 stroke or air-cooled.
I use a BERU 12-5DU myself recommend it highly. BERU has a slightly
different heat range scale and there 5 is between NGK 7 and 8. Perfect.
THE 12-5DU is the OEM plug for the air-cooled BMW boxers. There are two
versions, 37 with fixed SAE terminal and 36 with removable SAE terminal
which you need for the standard lead.. If you go to a Motocoil, it does
not matter because you will also need a new lead for that coil with SAE
terminals as well. I use and recommend BERU PowerCable:


obviuosly different lengths of the same cable 30, 50, and 60cm long.

I modify the BERU plug for myself and if requested:

After cutting short and bending in to the center electrode, I saw
between both electrodes with a calibrated saw to 0,7mm.