MZ/MuZ Riders

The ETZ is running rich (black spark plug) and runs poorly in lower engine revs - approx to half throttle where it then clears and picks up speed & runs as it should.

I've tried to adjust the carb with little luck - I can get it to tick over nicely (about 1200rpm) but anything less it becomes lumpy and won't idle.

Carb cleaned & checked and all appears well, timing & points gap is ok, new Champion plug fitted & air cleaner element clean too, all clips, rubbers etc are tight.

Is there a simple way perhaps to weaken the mixture via the pilot air screw without compramising tickover.

Presumably turning the screw out 'weakens' and in 'richens' the mixture.

Many thanks

Andy

Hi,

Has the choke plunger rubber seal perished, as this would cause your problem.

Nope, already checked and intact - its driving me nuts!

Maybe I've overlooked the obvious.........................?????????????????

Just some things to check:
Is the choke cable frayed? if so the choke plunger may be still open. Choke lever should be up when closed
Ensure that there is nothing in the frame tube, as the airbox breathes through this.
Fit an NGK plug, the projector nose type are better at not fouling.
Is the carburretor needle in the right groove, too high and you'll run rich.
Carb floats may be punctured.
Check oil pump to ensure its not over oiling.
Try running without an air filter, it could still be blocked even if it looks clean