MZ/MuZ Riders

When I have the Sport on its stand and its warmed up, a blip on the throttle and then snapping it shut to enjoy that lovely single blat blat, I get a puff off dark smoke from the can. Is this something to worry about or is it normal. I did wind the pilot screw out about 7-8 turns.

It does not smoke at any other time.....I was wondering if it was due to such a large piston drawing up oil when the carb slides are closed due to the large vacuum, is that logical?

Oil usually burns a misty blue, dark / black smoke is indicative of a rich mixture.

Why did you wind out the mixture screw so rich? 5 turns further in might sort your problem.......................

these bikes are bad about backfiring on overrun
and some have found that 4 to 6 turn out helps bring it to a level where it can be lived with,,

my ideal is get rid of the cv carb for some thing else
i rode BMW from 1969 to 1999 and still have some
the bing cv on the r75/5 i had need to be pitched in the junk behind the shed

the r90s i owned for 28 years had a dell'orto and was a winner

cv,s will work but finding some one that can work out the bugs is not worth the effort

the big problem is the gasoline is CRAP

It was the back firing and popping on a sharply closed throttle on the over run which made me turn the screw out so much. I got out to the garage and turned it in to 3 1/2 turns , it still runs OK on the stand, a bit less easy on the tick over so I had to turn the tick over screw in.....the tick over was best when it was out further though

But the black smoke is almost eliminated on blipping the throttle, just a whiff of vapour and the end of the can is dry , so a result there, thanks all

There's a diaphragm on the side of the CV carb which is designed to stop the overrun popping. If it has perished, you need to adjust the mixture screw to compensate for a weakness caused by the diaphragm. Worth a look, especially with ethanol in the fuel

Thanks for the tip, as we both know its freezing in Scotland just now so i'll wait for the weather to get warmer before I go for a roadtest.