00 WR400 Noisy Motor - timing chain?

Over the progresion of time my WR is getting quite a sort of air & metal noise about the engine.

It happens only once the bike is hot, never in idle, from about 1/4 to peak RPM. It is a engine noise as it happens whether the clutch is in or out, any gear, and it goes in tune with the engines RPM whether the bike is moving(in neutral) or stopped.

I have changed the oil, checked the level, for it to still occur. I have confirmed oil is reaching the top of the engine via undoing the bolt that connects an oil pipe(carby/kick starter side) to the top of the engine. Radiator's are full and both get hot with operation.

What could it be? Worn timing chain guides??

For that old car engine noise it makes, it still goes hard as if I've just bought it. Traveled 7000Kms(no tar work). 00 WR400.


I don't have a WR. I can checked the slack on the cam chain and know how much my KLX has worn. For my auto tensioner, I had to remove the bolt holding spring tension and put the bolt up to the spring. Without compressing the spring, there is an accepted amount of 'push' for me to get the tension bolt started in the auto-tensioner body. If it is less than 1/4", the chain is getting closer to replacement. Maybe some other WR owners know and can give you a short lesson of checking cam chain wear. They might know the accepted distance for spring tension and how it's measured. You can always try your local shop. Some are more willing to help than others depending on who works in back.

I built a manual tensioner with some advice from Burned and Jerry Leighton of stroker. I am no engineer, but I feel that the chain is running under a set tension, not constant tension. The difference is there may be a little more noise, but the chain is not under a continous bind. I couldn't tell you about long term, it only has a few hundred miles use on it at this time. The reason for changing it was the fear of auto-tensioner failure. My bike doesn't have a history of failure per se. Most new fourstrokes are auto-tensioned.

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