clunking noise when bike runs below 1200 rpm when hot.

G'day fella's i need some advice. Ive bought a 95 750 with 59,000kms. When i start up the bike from cold it sound magic but as the bike becomes warm it starts making a clunking noise that can be felt through the whole bike. The harder i ride it the louder it seems to be when pulling up to stop. Over 1200 rpm there is no noise. I have removed engine and had a look around for any thing obvious. I'm hoping its not the big end bearing. I found that if i grab the clutch basket i have about a 5 to 8 mm movement either way. The clutch outer housing does not move but the centre does. Is this normal or may i have found the problem.

Cheers

 

Slight variations in engine speed--due to poor throttle plate synch--tend to rock the clutch plates back and forth within the basket, making noise.

Uneven compression between cylinders could exacerbate the problem or cause it also.

A really accurate carb synch would be the first thing to try.

 

Agreed. I had the same issue with my '86 750 after doing a carb rebuild. Couldn't get the sync properly because the springs under the sync screws were crap. Replaced all the springs and did a bench sync, no more noise.