Loose Rear sprocket??!!

[Maynerz]

I have a YBR125.

Recently I noticed one audible click noise when pulling away from a stop, This noise could also be replicated by fulling easing off the gas then accelerating again causing the chain to sag then tension (Not sure that's the technical term).

Whilst cleaning my chain and sprockets I noticed my rear sprocket, which is a JT sprocket I believe, has movement where it could slightly rock forwards and backwards with not with the hub. It isn't the cush drive as I removed it from the rear wheel to eliminate this.

The tab washers which lock the four bolts in place hadn't budged but somehow the four screws had all come loose and allowed play between the rear sprocket and hub.

I thought I had tightened them down equally and adequately (although I cant find the torque settings anywhere) and am a bit myth-ed as to how they came loose.

The hub appears fine and my chain and wheel alignment was decent so I don't think this was the cause.

Does any one know what causes this issue as I know it has the potential to be an accident waiting to happen?


P.s I have ordered a new rear hub, tab washers, bolts and screws which are all Yamaha OEM. I will also we swapping out the chain and sprockets.

Kind Regards,

Jack
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2016 Yamaha ybr 124

[zark]

When the chain fell off my ybr, the sprocket carrier bearing had failed...

Just check all the bearings are good (wheel and sprocket carrier) and no free play that might make things wobble
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CBT - Oct 13. Theory - July 14. Mod 1 & 2 - June 15.
Rides a Fazer like an idiot... Edit: Now ride a Fazer Thou...

[Maynerz]

I don't think there's any play in them however they're a cheap replacement so I shall swap them out. Cheers!
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2016 Yamaha ybr 124

[zark]

Now I think of it... The bolts screwed into a flat block on the inside of the carrier, that wedged in place when tightened.

Some of them stripped the thread when I tried to undo them. I couldn't be bothered to order new ones so replaced them with a nyloc locking nut (with the plastic insert) and never had any problems... If you still got the original nuts inside, check the threads
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CBT - Oct 13. Theory - July 14. Mod 1 & 2 - June 15.
Rides a Fazer like an idiot... Edit: Now ride a Fazer Thou...

[Maynerz]

I was doing a bit of research and apparently when a rear sprocket becomes loose because of the bolts it can warp the holes into the hub so it creates play and then it's a problem which will keep happening.

Nylocks seem like a good idea along with some locktite.

New hub and bolts are en route so hopefully that'll solve this issue!

Jack
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2016 Yamaha ybr 124

[MCN]

2016 125 and it needs a sprocket hub?

Do you use it off-road?

Is it under warranty?
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[Maynerz]

It is under warranty although I've fallen out with my local yamy dealership after put a new chain on sprocket on bow tight and caused the rear sprocket to become loose. That was at 11000 miles and it's now close to 15000 miles.

I'd rather do the work myself as it's more time efficient for me and I enjoy it.

I've taken it green lane-ing once...never again!

The hub only costs £12 and bolts and locks are only another £6 or so.

I use the bike almost daily for a 50mile round commute so it's getting it's fair wear.
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2016 Yamaha ybr 124

[ThatDippyTwat]

Edit:- Never mind, you call them tab washers, you know what they do.
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'98 VFR800 (touring) - '12 VFR800 Crosrunner (Commuting) - '01 KDX220 (Big Green Antisocial Machine)

[Kentol750]

50 miles a day on a ybr, why aren't you licensing up?
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Some bikes.

[Maynerz]

Just turned 24 so booking my das soon!

Can't wait for the power upgrade!
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2016 Yamaha ybr 124