MZ/MuZ Riders

Hello
some weeks ago I posted a topic about my 250 ETZ misfiring - and got a host of suggestions and ideas that I have put/am putting into place. Despite renewing coil/condenser/ht cap/plug /retiming I still couldn't get any go at bigger throttle openings - starts easily and goes fine up to 1/4 throttle. So I removed the silcencer to clean out with Caustic Soda and realised that the guts were jangling about. Out with the disc cutter and this is what I found


None of the bits had been attacked by a ham-fisted mechanic just as found. This would have meant that the gases were being impeded at best, and probably accounts for the misfiring malarkey, but would the normal firing explosions/beats within the silencer cause this sort of damage; and has anyone come across it before?

Not that every problem doesn't ahve a bright side - the carving up of the silencer now gives me the excuse to rebuild the silencer up out of the way for the trail version I ride. I've started with the header and reshaped it, trying not to blow too many holes tacking the thing up. Next is the rebuild of the silencer without changing the principal dims too much. Once all tacked up, I'll get a friend to Mig up. I'll sort out a flexible mount to accomodate the rubber mounted motor.

Hi Ricardo,

Sorry the only information I have about the insides of the ETZ silencer, are on my old 1988 ETZ 250 the baffle tubes were square not round like yours, so is yours a aftermarket pipe, just thinking maybe very bad build quality.

update - the exhaust is now rebuilt with all the baffles welded back up and new flex mounts added. Tried it out today - revelation - the mikuni plus clear exhaust have transformed the pick up, mid range acceleration, and it clearly flows much better. I could have omitted some of the baffles but MCC trials are through the night and noisy 2 strokes are somewhat frowned upon. Sorry about the photo, but phone camera is a bit iffy.



Once I've properly tested for leaks etc (seems ok) I'll paint or leave as is. I don't want pretty, just need effective.

Another photo

If your going to use and older Etz250 for cross country trials, I would certainly look into rigging up a sump bash plate and use the forward dowel hole (just under the exhaust) as one mounting point, and the either weld extension mounts to the rear engine mounting plates (no need for a flexable mount) , or us front foot rest mounting bolts as the rear mount (but this idea for a rear one would have to be flexable enough to allow for the engine bouncing on its isolastic head mount.)

Yes, thanks for that, troglodyte, I was thinking of doing something along those lines but you've just clarified my thinking.

What a great looking trail bike. Love the exhaust job. It somehow aesthetically - er - fits in with the squared shape of the bike's styling. Brilliant!

I also had a pattern silencer that gave up after 16000 miles. It is not easy to trace the problem, the silencer has better chrome than an MZ one and it wasn't the first thing I looked at.
These silencers cost 45 euros in the eurozone. They get more expensive if you pay in pounds in the gangsterzone, as I did.
I hope the welding job proves to be a lasting solution.
Louis

Yes - I hope it all hangs together. Next weekend (easter) is the Land's End Trial - 4 emzeds; there is another etz, a ts250 and a ts125 entered. we have extensively tested the exhaust - an 80 mile trail ride produced no exhaust problems just 2 rear punctures.
I've tidied it up a bit exhaust wise and fixed a steady at the joint between header pipe and silencer which will double as a bash plate mount when I get round to it, but no time now to complete. I'm quite pleased with the look, as the paint and the heat guard breaks up the missile launcher look. Pics -

That is a very nice little trail bike conversion you have done there.