2000 WR 400 cam tensioner help

I need a little tech help. My cam chain keeps skipping, I believe the tensioner has gone bad, but I'm not sure how to check it. It seems like the chain is tight and the tensioner is functioning (does the tensioner spring wear out?). The cams are in great shape, and the chain looks good. I re-set the cams to where they are supposed to be (at TDC), put it all back together, it starts and runs fine, but the next start-up it skips again. The bike still runs (out of time) but sounds like it will grenade at anytime, and i'm pretty sure it is doing damage inside to the valves. Anybody else have this problem? Any info would be great.

P.S. The Yamaha dealers have got me nowhere. All they say is replace the cams, tensioner, chain, and crank. All the stuff they want to sell me look fine. Some how i think they just want my money. LOL

You can buy a manual tensioner from the TT store. That will solve the dilema as to is it or is it not working.

First, have you checked the sprocket behind the stator? When you return it to the correct timing, do you have to adjust both cams or just one? If you think it is the tensioner, wind it up, remove it from the bike, and then release it. Try pushing in on it to see how much resistance it has. A new one will cost you about 40 bucks. I have the one that I pulled off my bike when I did a new top end, chain, cams, ect... There is nothing wrong with it. PM me if you want it.

The chain is pretty tight even without the tensioner... don't be fooled by how tight it is. You're tensioner could be totally busted you could probably not feel the difference on the chain. I would pay the fourty dollars and buy a new one right away and see if it solves the problem...Just my 2 cents...

First, have you checked the sprocket behind the stator? When you return it to the correct timing, do you have to adjust both cams or just one? If you think it is the tensioner, wind it up, remove it from the bike, and then release it. Try pushing in on it to see how much resistance it has.

The sprockets all look great and only the intake cam is off by 1/4 turn (or so). How much resistance should the tensioner have?

Checked the spare that I have and I can barely make it budge. I'm going to say really tight. Don't ride it until it's fixed. Your valves will hit the piston if it jumps time too much. So when you set the timing marks through the inspection hole, it's only the one cam that is off?

Checked the spare that I have and I can barely make it budge. I'm going to say really tight. Don't ride it until it's fixed. Your valves will hit the piston if it jumps time too much. So when you set the timing marks through the inspection hole, it's only the one cam that is off?

Only the intake side was off by 1/4 turn or so (Both times). I haven't had a chance to tear it apart again to confirm this. Here in Michigan it's still too cold to play outside. Thank you for the help. I will re-post for all to read when i repair it again. Hopefully these threads help someone else that might have the same issues, as much as it helped me. I love this site.

Again, my offer still stands. If not, 40$ is a cheap investment compared to piston and valve contact.

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