[Martin C]

Originally Posted by jerry

This is driving me mad,,, The bike runs but will NOT TICKOVER or run below 3k revs on rear cylinder ,front cylinder and carb are perfect,

I have rebuilt the carb 4 times now with new parts it has been thoroughly cleaned , in ultrasonic bath twice , blasted with air ,, each time I have fitted it the fault is still the same ,,it has new float , new gaskets, needle, airscrews, even the pilot air cutoff valve is new ,,,baffling ???
The right hand front cylinder carb is fine

I have put other spark plugs , HT leads , coils and igniter units they are from one of my other bikes but the fault persists so its not Electrical ,, There are NO airleaks I have now spent some 80 hours on thsi one problem and im run out of ideas ???? totally baffled

Pardon me for asking, but are you absolutely certain it’s a carb problem? My M900 once had a very similar problem that was caused by a poor coil wiring connection, almost no copper strands were intact inside apparently good insulation at the connector. At higher revs normal vibration was evidently enough to cause a better contact path.