1988 Ninja 600 drive train knock
Hello, I've noticed a knock below 4000 rpm while gradually accelerating. I can feel it in my foot pegs. Doesn't matter what gear I'm in or speed, and it disappears with the clutch pulled in or RPM greater than 5000. It's absent cruising or coasting, still idling great, shifting good, with only issue is an existing problem of getting it into neutral when its hot. Just looking at ideas of the what issue is.
Its a 1988 Ninja 600C, Canadian bike, with 46300 km (about 28000 mile) on it. It's been running good for the five years I've had it, with regular oil changes and chain maintenance.
Thanks in advance!