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I have a Yamaha XJ600 diversion with a sidecar fitted.

Recently had to fit two new tyres and a new rear sprocket for MOT.

Chain seemed fine afterwards for a while but all of a sudden started making a terrible noise. When I stopped and inspected it seemed the chain was really loose.

If the bike is pushed forward in gear(even with clutch pulled in) the chain is tight, but when rolled backwards it is really loose. It's also loose when rolled back or forward in neutral.

Thought about just tightening the chain but I'm worried that if I do then it will be too tight when on the go and could snap or cause damage.

Could it be the wheel alignment? Is the chain just loose and tightening up when tension is put on through pushing forward? Might the front sprocket be damaged? Or something completely different?

With the sidecar fitted it's awkward to get in to work on the bike (to check front sprocket etc) so thought I would ask and see if anyone knew what might be the problem first.

Thanks, Steven

DucatiKiller
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Steven
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1 Answers1

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High Spot

If I were to guess, you have a 'high spot' in your chain.

Cause

High spots have occur for a number of a reasons

  • Ongoing poor care

  • Low quality chain

  • 'Clutch Dumping' which causes stretching of the chain.

  • Water penetration of a few rollers leading to rust and inconsistent where on those rollers

Remedy

For now, adjust your chain to the highest point of tension. Roll the bike forward or backward in neutral and find where the chain is tightest. Adjust the rear wheel distance at that point.

Long term you will want to always change both of your sprockets and your chain at the same time. Why, you ask? Because they wear together as a team, so to speak. The surfaces of the rollers in the chain and distance of the rollers within the chain change with wear over time. As your chain wears it mates into the sprocket and they all wear together.

If you only change your sprocket and retain the old chain you can get a condition where the rollers on the chain are only 'loading' the last few teeth of the sprocket before they chain and sprocket separate.

If buy a bit of a higher-end chain your chances of getting stretch and having high and low spots on your chain over time will be reduced. With the most expensive chains that I purchase for my motorcycles I have nixed this issue and it doesn't occur for me. Typically chains with o-rings between the plates will have a longer life span than non o-ring chains as they will prevent moisture and rust in the roller because they are sealed with grease.

DucatiKiller
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