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XR4 cam chain

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My buddy had a Honda shop mechanic tell him that they suspected he needed a new timing chain. We just tore into the engine the chain seems tight and like it wouldn't skip any teeth. How can you tell if you need a new chain. There is a slight noise on the bottom end, my buddy said it sounds similar to his old Toyota's. I've heard that these engines make a lot of noise as it is.

Any help is appreciated!

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We just tore into the engine the chain seems tight and like it wouldn't skip any teeth. How can you tell if you need a new chain.

What did you take it to a mechanic for in the first place? Bottom end noise? If the bike has a skid plate on it, it can amplify engine noises and direct them upwards at you, making you think there's a problem.

We gauge chain wear/stretch by the amount of adjustment the auto tensioner has left in it.

With the tensioner mounted in the engine, Take the screw out of the center of the tensioner body. It's basically just acts as a plug. Insert a straight slot screwdriver. Turning the screwdriver retracts the tensioner plunger that puts tension on the chain. Pay attention to how much you turn the screwdriver from it's extended position to fully retracted.

Now remove the two bolts that mount the tensioner to the engine and pull the tensioner from the engine. Use the screwdriver again to find out how much turn it takes to retract the plunger from full out to full retracted.

Lets say it was 1/4 turn with the tensioner out of the engine and the same with it in the engine. That would tell you that the cam chain wear is at the limits of the tensioner to compensate for, so it needs replacing.

If screwdriver turn was less than 1/4 turn while in the engine, that would mean the tensioner still has a little adjustment in it to compensate for chain wear and the chain still has life left in it.

An important thing to check is to make sure the plunger springs back out on its own when you retract it and let it go. If it doesn't, it's torsion spring is broken and you need a new tensioner. That, or convert it to a manually adjusted tensioner. If the tensioners torsion spring is broken, the cam chain is running with a lot of slack and makes a hell of a racket. There may be nothing wrong with the chain at all.

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What did you take it to a mechanic for in the first place? Bottom end noise? If the bike has a skid plate on it, it can amplify engine noises and direct them upwards at you, making you think there's a problem.

We gauge chain wear/stretch by the amount of adjustment the auto tensioner has left in it.

With the tensioner mounted in the engine, Take the screw out of the center of the tensioner body. It's basically just acts as a plug. Insert a straight slot screwdriver. Turning the screwdriver retracts the tensioner plunger that puts tension on the chain. Pay attention to how much you turn the screwdriver from it's extended position to fully retracted.

Now remove the two bolts that mount the tensioner to the engine and pull the tensioner from the engine. Use the screwdriver again to find out how much turn it takes to retract the plunger from full out to full retracted.

Lets say it was 1/4 turn with the tensioner out of the engine and the same with it in the engine. That would tell you that the cam chain wear is at the limits of the tensioner to compensate for, so it needs replacing.

If screwdriver turn was less than 1/4 turn while in the engine, that would mean the tensioner still has a little adjustment in it to compensate for chain wear and the chain still has life left in it.

An important thing to check is to make sure the plunger springs back out on its own when you retract it and let it go. If it doesn't, it's torsion spring is broken and you need a new tensioner. That, or convert it to a manually adjusted tensioner. If the tensioners torsion spring is broken, the cam chain is running with a lot of slack and makes a hell of a racket. There may be nothing wrong with the chain at all.

Thanks for the reply! He took it in to do a basic service while he lived in a different place. They also told him his spoke nipples were seized....I checked them and only one or two were hard to move. I'm new to this so I may need to ask a couple of clairifying questions when we get back into it tomorrow. It does have a fairly burly skid plate.

Sorry for the ignorance, is a straight slot screwdriver a flathead?

You can barley move the chain on the sprocket.....I have just never seen the need for 100% tight chain, although I've never got into a cam chain.

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Sorry for the ignorance, is a straight slot screwdriver a flathead?

Yes, it's a flat tip.

Forgot to say, if you check for the amount of tensioner adjustment left as described earlier, make sure you don't let anyone kick the engine over while you have the tensioner out of the engine.

When you push on the chain with your finger to check for slack, you're putting more tension on it than the auto tensioner is doing. If it's obviously not real slack, then the tensioner is doing it's job and the chain is probably fine.

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