Help! Got a, mates 200 pro which suddenly started making hellish engine noise. He thought top end. Pulled it apart, mains and small & big end fine. Bore good. Stuck new size d piston set in. Clean carb & filter. Fired it up and still sounds s#*@e. I'm suspicious of clutch/ kick start/gearbox. Noise sounds like a knocking to me. It doesn't go away when you pull the clutch in, or under load, but does get slightly quieter. More dwarf than normal on the drain plug. What's the most likely culprit ? Also should there be any movement in the bush when I try to rock the whole clutch assembly? Cheers.

99% sure: The idle gear between kick start gear and clutch basket.

It probably looks somehow like this one:

-Jan

Edited August 21, 201313 yr by jandyb

A knocking at all speeds is probably a piece off the kick start gear traveled to the primary gear. (big gear on the back of the clutch) Usually sounds like a rod knocking, hardly visible by the eye. Some times you need to take an eyeglass to see it.

Thanks for the excellent advice. Pulled the clutch and sure enough the idle gear looks pretty rough. Is it recommended to change the idle gear and kickstart pawl together? the teeth on the pawl don't look broken, but then without a new one to compare I can't tell if they're too badly worn. Thought this might save splitting the cases but the main shaft seems to have play in the bearing and the plastic kickstart stop is broken, so it looks like a full rebuild with new gearbox bearing kit. When I pulled the clutch the two bearings came out and dropped needles. If the bearings are in good condition should the needles stay captive and is this an indication that the bearings are shot, or are they always loose in the cage?

Cheers

The needles should not of fallen out. I believe that there is a new single bearing. Was this bike just recently bought? The kick start pawl is usually pretty obvious if broken.

The kickstart pawl has some wear on a couple of teeth. Theyre worn down on one side and no longer square. I think the bike has had a lot of schoolboy use. it's an 06. When my mate bought it he had the crank rebuilt and new mains and seals. He thought it had been a 125 that had a 200 kit fitted. It's since had a new piston kit and is on a size D piston. I think it's just well used and now needing a thorough gearbox rebuild.