Clunking under acceleration, felt through left peg

[nrx_red]

Can anyone help me with this problem I am having with my 2003 FZS600? For the last 2 weeks, every time I open it up, there is a clunking coming from the back end.  This can be felt through the seat and left footpeg and only occurs under drive.  There is no noise when coasting or slowing down.  I couldn't see anything wrong, so I've had the back wheel out, and one of the wheel bearings was a little noisy (30,000 miles on it), so I've swapped them out, but the clunking is still there.  The front sprocket nut is solid (I've had that come off before) and there is no movement in the swingarm. The chain and sprockets are fairly recent and the chain looks to run over the sprockets smoothly when turned by hand. I've seen some other posts about tight links in the chain, but judging by the amount the chain jumps about on the main stand (about 100mm), I think it is something more serious or is this how bad it gets with a tight link? I don't want the hassle of taking it to the dealer if I can fix it, but I've run out of ideas!

[andybesy]

I had very similar symptoms after a long day's riding and lots of miles during recent tour. It was ok once you got up in to higher gears but in first and second in particular and third to lesser extent even quite gentle acceleration load caused some really horrid clunks, both heard and felt. Interestingly came on quite suddenly, didn't develop slowly throughout day.

Good lube of the chain sorted it, was worried that the dry lube the group had bought wouldn't do the job but was nice and smooth again next morning.

What you using no the chain? How much slay does it have side to side and when pulled away from rear sprocket?

Suggest a good degrease and soak in lube first thing to try, I use engine oil makes mess and washes off in rain but penetrates well.

[darrsi]

Chain jumping about on centre stand is normal, caused by wheel momentum with no weight load, the chain is stopping the wheel from overtaking it so flaps about a bit.
You are describing either a tight link, or a misaligned rear wheel.
Move the wheel slowly on centre stand and look for links that aren't as totally horizontal as the others, if there is one or more it will actually be quite obvious, normally sticking at a slight angle aiming upwards from bottom left to top right when viewing the lower part of the chain.
Ideally, if this is the case, it will need a good lube or soak in paraffin or oil overnight and maybe try and work the link free with pliers. This can work but isn't always successful, or won't last long either, unless you're very lucky.
The trick is to keep the chain heavily lubed all the time, it doesn't take much time in bad weather to dry a joint out, especially if left out in the elements.
Other option is offset rear wheel, that may be coupled with an overtightened chain.
Had it myself a few days ago, a new mechanic i've not used before fitted a new chain and sprockets for me but i kept feeling something a bit lumpy on the left foot and when i checked the markings they were different each side by about 1.75 notches......i wasn't impressed!!  :rolleyes
Took my time levelling them up properly, with proper chain slack, and all is well now. 

[nrx_red]

Thanks for the replies guys, I never thought that a tight spot in the chain could cause so much problem; I've always had a Scottoiler fitted, so I am very lazy at checking the chain!
Wheel alignment is OK, as I always install it myself after tyre changes etc. and use a steel rule to get it bob on.
Had a look at the chain last night and couldn't see a tight spot until I started checking link by link and found that it was every other one!  I've given the chain a good clean, lathered it in engine oil and spent a couple of boring hours working each link until they all moved freely.  I've left the tightest one (it's the joining link) sitting in a bowl of oil for the day to see if I can get it properly slick again. I'll give it a go tonight  :rolleyes .

[Jamieg285]

Having had a stiff link problem recently, I can confirm that the clunking is most noticeable at lower speeds. Once you get faster, the frequency goes up and it's less noticeable and becomes more of a buzz that a clonk.