Unusual clunk

[BribieDuc]

Riding to work today, and I heard a few clunks coming from below, probably from the rear - a little hard to tell.
Happened at low speed.  Also noticed when at the lights the bike would only roll backwards a foot or so before it locked up...in neutral and with clutch in.   Moved freely forwards. Clunk sounds happened again shortly afterwards and bike now rolls freely backwards. Suspect I also heard similar sounds yesterday. Had a quick look on arrival at work, thinking something might be loose but couldn't see or feel anything.

Anyone have this happen before or have thoughts on the cause. I'm thinking something might be coming loose and swinging into the wheel  ... brakes seem fine, chain's okay, engine is running fine...gearbox (although the clunking sounds external) maybe? Bike has a few miles on it but its well maintained.

Thanks for any advice.

John

[erkishhorde]

Sounds like broken teeth on one or both of your sprockets. This could also indicate that your chain has gone bad. Did you take it off to inspect it or just look at it while the bike was on the side stand? I would put it up on a rear stand and spin the wheel to inspect the front and rear sprockets. If you see any broken teeth you should take off your chain and inspect it by hand.

Oh yeah, if you can't figure out what it is and you hear a "ping" or "pop" in the next day or two that's likely a tooth of the sprocket being broken off.

[Speeddog]

Yeah, get it up on a stand and spin the wheel.

Pull the cover to look at your front sprocket.

How many miles on the bike?
Chain last replaced when?

[BribieDuc]

Thanks for all the inputs (Tech and Oz Monster). 

Last night I put her up and checked all the suggestions:

Chain - a minor tight spot, RK racing X-chain
Sprockets - not too bad
Wheel Bearing - no lateral movement
Brakes - all there, tight, well off the wear line.

Found no problems...so simply re-tensioned everything and gave all an extra good lube. Will replace the wheel bearing at the next service (front was done at 75K, now at 98K).

300 kms on and no re-occurrance...although I'm listening   

Again, THANKS 

[2-Wheelin Hooligan]

Keep us updated please.  I'm having similar problems but to the point I can feel it when a clunk occurs. 

[EEL]

Thanks for all the inputs (Tech and Oz Monster). 

Last night I put her up and checked all the suggestions:

Chain - a minor tight spot, RK racing X-chain
Sprockets - not too bad
Wheel Bearing - no lateral movement
Brakes - all there, tight, well off the wear line.

Found no problems...so simply re-tensioned everything and gave all an extra good lube. Will replace the wheel bearing at the next service (front was done at 75K, now at 98K).

You have a 620 ie. Is it possible that one of the adjuster plates for axle alignment is loose?

300 kms on and no re-occurrance...although I'm listening   

Again, THANKS