2007 WR450 Crank Issues

I own a 2007 WR450 with maybe 50hrs on it. It has been well maintained and not drowned in water or anything. A few days ago I noticed a loud sound coming from the engine so I took it in to the shop. I thought it needed a valve adjustment but I had them adjusted when the bike was around 30hrs. Well the guys at the shop Adjusted the valves then noticed the timing waas streched. Upon further inspection they noticed the chain tensioner had failed. They replaced the chain and tensioner, adjusted the valves and started the bike. The bike still made the loud clicking/clanking sound. They told me it is probably the main bearing on the crank shaft and to ride it until the engine quits running! They said the cost of the repair after total failure will be nearly as much as fixing it now and they may not be able to find the problem anyway until total failure. So here's my questions.

1- Have you ever heard of a chain tensioner failing on a bike this new?

2- What would cause the timing chain to strech?

3- Have you ever heard of a problem like this before?

4- Should I keep riding the bike? Other then the noise the bike seems to run fine.

Thanks for your help


Hmmmm....sounds like they screwed up and didn't release the tensioner when they did the valve adjustment. Hopefully the crank gear is ok since it is machined as part of the crank assy and cannot be replaced seperately. I'd pull the flywheel and get a good look everything. I doubt the main bearings failed. Probably more likely still some problem in the valve train drive. If a shop advised me to ride it till it blows up I'd be looking for a new shop!

Find another shop! There should have been nothing to adjust at 30 hours of run time. They would check them and find them all in spec I bet. Ask them what shims they used to get the proper clearance? The cam chain tensioner would pop out on its own if left in, plus the worst problem would be the chain jumping on the cams. I would find another WR to listen to first as they do make noise you might be looking for a problem when its not there.

Same as above, get it checked by someone else as it could get more expensive. If your timing goes out again for the same reason you initially took it in you could screw your top end. That happened to me recently. My timing went out because of some type of failure (not sure if it was the tensioner or some other reason) and I ended up dropping three inlet valves, which screwed the head, valves, pot and piston.

I'll almost gurantee the only thing wrong with your bike is an unevenly stretched and worn drive chain. The chain slapping on the swingarm slider sounds like something giving in the motor. Repalce the chain and both sprockets and report back. Simple things first....

The '07, like all earlier 450's, has a considerable amount of primary gear backlash. This combined with the aluminum frame and a WR skid plate make the engine uncomfortably noisey, but there's nothing wrong with it. For comparison, listen to any '06 0r '07 YZ450 at idle.

The '08 has reduced gear lash, and so is somewhat quieter.

On the cam chain, there have been a small number of reported failures of chain tensioners that resulted in the chain becoming severely kinked at low hours. Not many.

Find a new shop.

If there is something wrong and the motor grenades you'll have to take out a second mortgage to fix it.

The aluminum WR's are noisy but if the bike suddenly starts making noises something is wrong.

Thanks for the replies.

I plan on taking it to anouther shop in the next couple of days to have them listen to it. There is definetly a problem though, one of my riding buddies has the same bike and it definetly does not sound the same as his.

Do you think the shop sugested I keep riding the bike until it blows up to hide the fact they screwed up? Could they have dropped a shim or something down into the crank by means of the timming chain? Man this might get dirty.

120hrs on my bike still going strong and untouched

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