Problem?!?!?!? Need help

Was out riding last month in some serious heat and boiled the coolant in some slower single track stuff. Shut the bike off right away and let it cool down. Rode it multiple times since then without problem but the other day I noticed that while idling when I put it in neutral and let off the clutch a humming somewhat grinding noise appears. And it only appears when i let up off the clutch not while i got the lever pulled- almost like its engaging but not moving???? This is definately new. It never made this kind of noise before. Does this have something to do with the overheating incident or is my clutch staring to go? Its an '04 wr450 and has only been ridden half of last year and only some of this year. I don't really abuse the clutch either.

Though it's damn near impossible to diagnose a problem like this without the bike itself, I'd go about it this way. Change the oil/filter and see if anything nasty comes out with it, i.e. metal chunks or lots of shiny glitter-like material indicating friction plate wear. Then, I'd pull the clutch cover and check all your plates. If your friction plates look blackened or burned, change them out. Same thing if the steel plates have blued. Check the teeth on the basket looking for grooves that will prevent the plates from operating smoothly. If it's groovy, replace the basket. Overheating and boiling your coolant is pretty common for the WR, so the clutch noise may or may not be related to the incident. If that doesn't identify or fix the problem, then I'd be thinking tranny and getting ready to dip into the home equity loan, but first things first...SC

I doubt it's related to the overheating. I'd start by checking out the clutch (plates, basket, etc) and see how things look.


Thanks guys- Is it likely that overheating damaged something else like warping metal or frying something up??

I have had mine boiling over on more than 5 occasions, and have not seen any adverse reactions. I would not worry about it overheating just that once, it is most likely unrelated to the current situation. Like stated above, pull the clutch cover and take a look. There is not going to be a magic bullet here, you will just have to find what is causing your noise and fix it. Hope this helps, if you get in there and are not sure then post some pics of your parts and you will get more help than you can shake a stick at. This forum is really great about helping those who don't know for sure what they are looking at.


All YZ/WR450F's make a noise like that. Whether yours is abnormal is best determined by a comparison to a couple of others.

The noise results from the fact that the engine doesn't idle at a constant speed.

It accelerates abruptly on each power stroke, and decelerates nearly as fast when it hits compression. To the transmission, this is like standing up in a bus while the driver plays with the brake and gas pedals, and the gears rattle back and forth in response. Even stick shift cars do the same thing (4 cylinders are worse than 6's are worse than 8's). The pattern is a growling rattle at idle with the clutch engaged that goes away when you pull the clutch and/or put the bike in gear. Check a couple of other bikes before you get worried. :thumbsup:

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