Chain guard wear - .: XT660.com

Badgerflame · # 1 11-09-16, 14:07

Was out on a spin yesterday and the rear of the bike became very unstable around 95mph. Got on to some slow windy roads and something didn't feel/sound right.

Pulled in and spotted this wear on the chain guard

Done a bit of reading here and concluded my chain needed adjusting. So came out to shed put the bike on centre stand and switched it on and put it into gear and there is some definite lateral movement of the chain from biting into the chain guard.

So I took off the front sprocket cover for a look and there is a lot of material built up on the inside of it and around that horseshoe shapes sprocket guard

With some definite wear inside front sprocket cover too.

Debris around front sprocket

Front side of chain guard

Any ideas?
Thanks

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Pleiades · # 2 11-09-16, 17:44

Looks to me like your chain has spent a lot of time running loose? Judging by the build up of chain lube in there I don't think the cover has been off in a while and it kind of hints at the fact that the previous owners chain maintenance regime wasn't that great? All that build up just attracts dirt and grit and ends up like grinding paste and continually rubs on the chain.

Maybe that the chain is goosed? What is the condition of the sprockets like? How much lateral and longitudinal movement is there in the chain? Worn cush drive rubbers and/or a sloppy sprocket carrier bearing can cause premature chain wear and excess lateral movement. What are they like too?

Badgerflame · # 3 11-09-16, 19:14

Quote:

Originally Posted by Pleiades

Looks to me like your chain has spent a lot of time running loose? Judging by the build up of chain lube in there I don't think the cover has been off in a while and it kind of hints at the fact that the previous owners chain maintenance regime wasn't that great? All that build up just attracts dirt and grit and ends up like grinding paste and continually rubs on the chain.

Maybe that the chain is goosed? What is the condition of the sprockets like? How much lateral and longitudinal movement is there in the chain? Worn cush drive rubbers and/or a sloppy sprocket carrier bearing can cause premature chain wear and excess lateral movement. What are they like too?

Chain and rear sprocket only have 1000 miles-ish. I had to replace them the week after I bought it because as you suggested previous owner didn't take much care. So i reckon yes,that sprocket cover hasn't been off in a long time. Front sprocket itself looked fine.

I cleaned everything up. Checked the chain tension again and Lubed it. Checked the back wheel for bearing play. And there was the slightest bit if movement, Maybe 1mm. and I brought the bike to the garage to check tyre pressure and they were both low. Front 27, back 27. So I filled them to 31 & 33psi respectively. I'm hoping this and the bearing play will resolve /explain the issue.

Thanks as always for the help

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Badgerflame · # 4 11-09-16, 19:18

Quote:

Originally Posted by Pepsi

Is / was there any metallic fragments within the that old, black, lube paste (goop)? Looks a bit like it from here.

From your 1st picture, however, your chain looks brand new. There appears to be no dirt on any of the links (other than pick-up from the front sprocket 'goop bath'), or between the plates and there doesn't appear to be any fresh lube either.

Your 4th and 5th shots show what appears to be the outside edges ( outside as the chain rotates around the sprocket) of the chain having been chamfered off compared to the inner edges. Those shots look like your outer edges of the chain have been running against metal and filing away, but this would normally wear the aluminium the chain contacts 1st before the chain gets chamfered. Is there anything steel the chain is touching?

If this is the case, I would ask; is your front sprocket too big as it may be "overtoothed", or even too far out on the sprocket shaft? The 5th photo also appears to show a clean front sprocket (possibly new) owing to the fact that the threads that are shown are very clean for a sprocket that lives in an oily cave all its life.

I'll stick my neck out and say your new VX2 chain and sprockets are possibly wearing fast and causing metallic grime due to the fact the front sprocket is over sized for its available space, (possibly an incorrect multi-application sprocket for several bikes). Couple this with the fact the chain may have been too loose and this has added to the chain's ability to rub where it shouldn't touch.

Many, many apologies if the above is all utter tosh. Just going on what I can see.

I poked around in the goop with the screwdiver, and No metal as far as I could see. Chain and rear sprocket are new. Front sprocket looks factory as far as I could tell. I'll have a right look later and count teeth. I'll also check for that outer edge wear you were talking about.

Is it normal for the chain to eat into the plastic guard like that?

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Pleiades · # 5 11-09-16, 19:29

Quote:

Originally Posted by Badgerflame

Is it normal for the chain to eat into the plastic guard like that?

Yes if the chain is loose (and the swingarm protector/guide). However, are you sure it's cut into the plastic? They sometimes look like they have because of the neatly shaped build up of black crud that the chain has shaped. Clean it all off and you may be surprised that it's not as bad as you first thought...

Badgerflame · # 6 11-09-16, 19:35

Quote:

Originally Posted by Pleiades

Yes if the chain is loose (and the swingarm protector/guide). However, are you sure it's cut into the plastic? They sometimes look like they have because of the neatly shaped build up of black crud that the chain has shaped. Clean it all off and you may be surprised that it's not as bad as you first thought...

I'll check now. I thought the sprocket cover was damaged from the chain before I cleaned it. Hadn't thought of cleaning top of guard under the chain.

Cheers for all the help

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Badgerflame · # 7 11-09-16, 19:34

Quote:

Originally Posted by Pepsi

talking of new rear sprockets, did you get a standard sprocket? Sometimes chain slap is the result of 'adjusted' / incorrect sizing.

Local mechanic ordered it for me. No idea of size

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