Smoking exhaust

[andygbsmith]

I know from what I have read that heavy braking can cause lots of smoke from the exhausts and there is nothing to worry about but I notice on my bike that if I shut off hard and then re,accelerate I get smoke from just the left hand side.It is also slightly smokey when I pull away from cold sometimes.any thoughts or is this normal.Andy

[Richard Negus]

Andy,Light smoking is normal as all the engine lubricating oil gets burned, but heavy smoking suggests either some maintenance or a change of riding style is needed.There is plastic pipe connecting the left hand inlet pipe to the frame which is there to continually suck liquid oil out of the bottom of the frame. If there is too much condensed oil, the pipe passes a big glob of oil all at once, resulting in smoke in the exhaust. This always happens on the over-run, when induction depression is high.Too much oil can be the result of :-. the oil pump cable adjustment is set too 'rich'. the oil pump cable is kinked or corroded and sticking in the fully or partially open position. the cable outer has been accidentally pulled out of its ferrule, but hidden by the rubber boot at the gearbox endVery occasionally, the end of the scavenge pipe can become blocked by pieces of carbon and the bottom of the frame is full of oil up to the point where it floods over into the carburettors.If you use the smoothness of the engine to ride in 5th at traffic speeds, large throttle openings will deliver more oil than is required and encourage smoking.If all else fails, then change to a low-smoke synthetic two-stroke oil. Usually smells much nicer too!R.