Transmission - maybe?

[Dandy D]

Apologies for the length:

So I was riding Friday night touring around a new neighbourhood with a friend - going really slow. I noticed a knocking that changed frequency with the speed of the bike, not the engine rpm. I thought that it was just the brake pad just tapping the disk or maybe a rock caught in there somewhere. Anyway didn't think too much of it. Kept riding, went out on the highway and got up to speed.

I passed an oil truck (ouch! - get it?), anyway, in doing so I hit about 140kph then slowed to about 110. Everything is good. Shortly after that I started to twist it up a little and then the vibration started. Pretty bad actually - made my feet tingle almost to the point of pain. I pulled off to the side of the road to check over some things and to check the oil. Couldn't find anything obvious. Kept riding but the vibration was still there so babied it for the rest of the evening. When I got home I put my bike up on the center stand and rotated the wheel by hand.

There is a very audible knocking that I thought was coming from the front sprocket area. That sprocket was replaced along with the chain and rear sprocket about 600 kms ago. Funny thing is - there is no knocking when I spin the wheel in reverse. BTW the engine power seems to be the same as before this started. However I haven't taken it past about 5500rpm since this noise / vibration thing. Also, the knocking doesn't occur at the same place in the chain i.e., as in one knock per revolution of chain - it's more frequent than that but somewhat irregular.

So this got me concerned and Sat morning I dropped into the bike shop (Alberta Cycle for anyone who knows or cares) for the guys to have a quick look. The service manager listened here and there and back here then over there and said that sometimes the sound even seems to be coming from the top of the engine. All this happens when in neutral or in gear with the engine running or not. He got thinking that it might be a transmission issue but with only 21,000kms he felt that that shouldn't be happening. He did notice that even just running in 1st gear on the center stand that the bike was vibrating a lot more than what it should be even though, as he put it, these are not the smoothest running bikes out there. He seemed puzzeled.

So being the non-mechanic that I am, I booked an appointment for Thursday for a professional (= $$) to take a look at it.

Anybody out there have any ideas as to what might be happening or had a similar experience?  :dunno:   Thanks.
Dandy D

[Blueknyt]

hmm


without hearing and seeing myself i cant even begin, the list is too long.

[ktrim]

could be a broken spring in the clutch,  this will make the entire assembly out of balance.  it will also cause a knock that is hard to diagnose as it will transfer to both the transmission and engine

[Dandy D]

Yeah that's kinda what I thought - needs a doctor's touch I guess to figure this one out.
I'll let you guys know the diagnosis and the $$  :x  when I do.
Thanks
Dandy

[matt_not_andrew]

I think I may have the same problem on my 2003 GS here in the UK.  I've noticed a weird "pulsing / knocking" that seems to be coming from the transmission.  At first I thought it was my wheels out of alignment but after the garage straightened them out its still there.

It gets more prevalent with speed, and you can even hear it when running the bike in gear on the centre stand (don't try that at home folks.)

Can you let me know what your garages diagnosis was/is as I'm gonna have to take mine in too.

Any info is greatly appreciated.

Thanks,
Matt

[Gisser]

Funny thing is - there is no knocking when I spin the wheel in reverse.

How 'bout when you spin the wheel forward?  Any knock?  Because, there's not much happening within the engine cases when you spin the wheel in neutral.  Fifth and sixth gear and the ball bearing by the sprocket is 'bout all the moving parts in play.  This sort of diagnosis is a process of elimination.