chain jumping when in gear...

[Dangle_kt]

Hi,


Took the fazer for its first proper ride out the other day.


Went to snake pass, and despite my slow a55 riding, I enjoyed myself - the renthal low bars worked very nice (except being a bit vibey sending my fingers to sleep - balance carbs?)


Anyway, I must have done 150 miles over the day, but on the last 10 miles the bikes started making a horrible "DUNK", or "CLUNK DUN" every few seconds from the drive chain area.


I nursed it home very gingerly as the whole bike seemed to stutter and lurch as it did it.


I had a look today, assuming the front sprocket had worked its way off (heard this is common issue) - but the sprocket is fine - thought it might be the chain, so I adjusted and oiled it - that was fine too with no lumpy issues when rolling the rear wheel on the centre stand.


So next I banged it into gear and THERE it was, every few seconds the chain jumped - it looked as if the front sprocket was locking for a micro second every few revolutions, same through the gears...however


it DOESN'T happen if I pulled the clutch, I could pull the clutch in and it would carry on spinning nicely, so dramas, and then as soon as I let it out it would come back.


So I think it is something to do with the clutch (I guess ti wont be gearbox if it happens in all the gears..)


Anyway, before I whip the side case off and strip the clutch, any bright ideas about what it might be?


The bike has 50k miles on it, and not very pretty - but not had any issues till this (I commuted on it daily last year for a month or so, and did one track day session the other week when the local track let newbs have one 20 min go for £10!)


Thanks

[His Dudeness]

sounds like a tight spot in the chain. try rotating each individual link with two pliers and see if there's any stiff links.

[Dangle_kt]

Yeah I read of that, but it doesn;t do it when the clutch is pulled in - the rear wheel is still spinning as fast, but it runs smoothly.

[His Dudeness]

it could be clutch related but my opinion is rule out the simple things first and to me what you've described there warrants checking the chain first. if its not the chain then go deeper.

[darrsi]

I've just had the 'tight spot' stiff link issue, and you won't necessarily see or hear it jumping when moving the wheel by hand.The chain will jump on the centre stand anyway simply because of the momentum of the wheel with no weight or pull on it, the chain is just playing catch up.When you pull the clutch in you're not pulling the wheel any more, it's just rolling on it's own until it stops.Move the chain very slowly and examine each link by hand, on my chain the one that was stiff was slightly offset and looking out of place compared to the others.Whereas the others were all nicely flat in a line this one link was slightly pointing downwards.If you find one (or more), then use pliers on the edge of the outer link to try and move it from side to side, it will feel much tighter compared to the others, presuming the chain is in generally good condition, and kept well lubricated?I've been lucky for now and managed to free my link up by constant lubing and one night of soaking that part of the chain in WD40, then re-lubing daily and it seems fine at the moment, but i've bought a spare link if it plays up again as the chain has low mileage on it.Obviously worse case scenario is new sprockets and chain, depending on age, condition and mileage!!

[AdieR]

I'd be checking the chain quite thoroughly.

What age / mileage is on that chain?

[Dangle_kt]

I'm happy to check each link, but can anyone explain why it wouldn't happen with the clutch pulled in? It was still spinning as fast... but it smoothed right out.

[Strifae]

With the clutch in its free rolling with no added force to pull the chain around - it may be going same speed but is in fact slowing down - with the drive pulling on the chain the added force could cause it to do what you say

[Dangle_kt]

thanks - it still doesn't seem logical but as has been said - its a cheap fix if that is all it is!


Just got to wait for the rain to stop now...

[Dead Eye]

I've noticed that when the bike is cold the revs aren't perfectly stable until it warms up a fair bit. Even then it flickers about a little which is more than likely a sign of needing the cards balanced. This up and down in the revs will causes excess pull on the chain and cause it to jump then not because the tension has dropped - I can't see it being a problem. As someone mentioned before, when the bike is on the ground and loaded it up, there is a significant amount of force on the wheel which mostly prevents it.

[Dangle_kt]

right - the plot thickens


I was merrily testing the chain tonight with a set of pliers, rotating each link and found no tight links... BUT


I did find something else!


As I was rotating the link it was pulling the chain tighter, and there was a noticeable DONK noise - after further trial and error its seems like when the chain is under tension the rear wheel MOVES ever so slightly.


I thought it was bearings, but when I grasp the rear wheel and try to twist it (hands at 12/6, or hands at 3/9 oclock) it doesn't budge - but if I pull the entire wheel towards me it does move fractionally and makes the noise.


I thought it might be the swingarm moving, but its not - its definatly the wheel.


So essentially what is happening is the chain (when under load) is pulling the wheel around making the clonk noise and messing up the chain alignment fractionally.


So my question to you guys before I strip it is - what could it be?


I'm concerned I'll strip it and not find anything obvious as it is not THAT much play.


Few options I'm unsure on - cush drive? wheel spacer issue? Bearing issue that hasn't shown up any normal play?


Thoughts anyone?


thanks

[darrsi]

Are your rear wheel adjusters and rear axle bolt tight, and aligned properly using the swing arm markings???  :rolleyes

[Dangle_kt]

I will recheck, but yes - axle was tight, as were adjusters and the markings were both on the same line - plus the noise started when I hadn't touched the chain for months, I adjusted the chain and it carried on.

[CRH]

remove the rear wheel shaft  and chk that its not bent?....also it just might be the front drive shaft bearing??....if the chains been over tightened at some point it may have putt excessive load on shaft bearing and fkd it?  :rolleyes hence the slight play?

[glynblue2]

you state the rear wheel is tight is that your tight or tourque tight?remove the chain completely remove the rear wheel replace the rear wheel and re-torque do nothing else but this then you will have a starting point,if the movement is still there remove the rear wheel again and check everything,if you are sure its the wheel moving then it can be a number of things but visibly check everything first,then come back and let me know what you find?

[glynblue2]

having re read your description i would still do the above but i would say your bearings require replacement.whilst doing them also do the seals and do not power wash the rear bearing areas as this removes all the grease from them,also apply enough grease when you do replace bearings and clean the axle and grease this as well.

[darrsi]

The rear wheel shouldn't move at all when pulled, so if it were the front drive bearings that were iffy i'd imagine the chain being messy and jumpy but the wheel itself should still be firmly in place, and his left foot would feel like someone was kicking it?


Are you definite that you can move the wheel, or could it possibly be the chain/sprocket making the donk noise because they are simply severely worn?


The little giveaway is when you say you hadn't touched the chain for months, taking into account how much rain we've had this year!


The reason i say that is 'cos i had a tight link on my chain and i really look after mine, but months of rainfall can take it's toll.

[Fazerider]

Very odd. If any of the spacers was absent then the axle wouldn't torque up to spec so it sounds more like a bearing must have gone. On the other hand it's hard to see how a failing bearing could give axial play without being detectable by rocking the wheel.
I can only suggest taking the wheel off and checking the three bearings... a length of tapered dowel to temporarily jam into the central hole makes it easy to check for play with them in-situ.
It's certainly worth doing soon, once a bearing starts to go it gets worse very quickly... the hardened surface material is not only no longer protecting the softer underlying metal, but the ground-up bits are now an abrasive that accelerates the damage.

[darrsi]

I'm starting to think you may be better off getting a professional diagnosis to be honest, i'd be inclined to get it down to the local bike shop and let a mechanic have a butchers! 

[darrsi]

I have been doing a bit of Googling on behalf of an issue with my bike and stumbled on an article where someone was complaining about a 'clonking' noise and it turned out to be very worn cush drive rubbers and the sprocket holder had no tension on it at all, so i s'pose that could be mistaken for movement in the rear wheel?
Apparently it can also be responsible for jerky running at low revs as well.