strange noise from cam chain side?

My buddies 01 250f has started to make a wrrr-wrrr sounding noise. It seems to be coming from the cam chain side of the engine. It starts as the bike gets hot anf gets louder the hotter the bike is. The cam chain tenioner is working, nothing seems to be rubbing when peering down the cam chain side. The noise isnt effected by the clutch but is effected by rpm. Any Ideas?

I started my 02 WR up and listened to the motor,checking the left side and nothing was apparent.I wonder if the magneto could be loose?Doubt that.

Just check everything you can think of.It could be simple.

How's the tension on the cam chain? even if the tensioner is working it could be stretched enough to be loose.

How's the tension on the cam chain? even if the tensioner is working it could be stretched enough to be loose.

That very well could be. 01 that 2+ years on that chain. They don't cost much and it wouldn't hurt to replace it anyway.

I have a 01 YZ250F, and I'm still running the original timing chain. Stretch and wear is still minimal on the chain, and no I am not easy on the bike at all!!!

Not saying that it isn't the timing chain, but could you try to pin-point the area that the noise is coming from.

Ex; Top of head, base of head, near magneto.

This would help out in trying to solve the problem better, instead of just saying "Yup, it's the timing chain".

For the cam chain to stretch so much that the tensioner couldn't apply pressure to it anymore, would cause the cam timing to be off so bad that you would notice a difference in starting or performance.

Has your buddy noticed this at all?

Get some more detailed info for us so we can dig a little deeper before he goes tearing the motor down.

You should be able to remove the bolt at the end of the tensioner and SLIGHTLY turn the slotted bolt inside with the engine running. As you know, this will increase and decrease the tension on the cam chain. If the sound of the noise changes you know it is one of the cam system parts. Just be careful not to tighten or back it out too much.

Downshift and gas it!!!

remove the bolt at the end of the tensioner and SLIGHTLY turn the slotted bolt inside with the engine running.

no offense, but this technique is a good way to instantly and completely wad your motor. once the tiniest first bit of slack shows up in the timing chain, the intake cam sprocket will slip throwing the timing way off and KaBooMie, piston and valves collide. :)

You are right, it isn’t the preferred method, but it does work. I would agree with you especially if the motor is revved up and you loosen it quite a bit but if you are careful on the stand at idle you should be ok. An unusual noise sometimes is an indication that the cam chain tensioner is bad and that noise is caused by the slack in the chain. This is because of inadiquite pressure of the tensioner (binding, weak spring). Most of the time riders finish the day with the noise/slack. And a few doen't.

I have checked the tensioner on many bikes this way without any ill effects, maybe I've been just lucky?????

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