2009 450 engine and or clutch problem?

Something has gone wrong on my 2009 YZ450.

  • The power seems to be slipping when i get on the gas, the bike has a feeling like the back tire it spinning from 1/4 to 1/2 throttle, after a second it would feel like the power returned.
  • My oil turned dark gray, a few small metal pieces in the oil.
  • Engine has a burning smell while running and after running.

I rebuilt my engine a few months ago and have 9 hours on it, I changed my oil at 1 hr, 5hr and 8hr and it was always a normal brown color.


My question is what is causing this, Is it the clutch? When i am sitting in gear and pull in the clutch the bike doesn't creep forward. Clutch is original and I attached an image of it.


Any ideas?

2014-07-20 16.07.23.jpg

Sounds like the clutch plates are shot. Replace those metal and friction. Also it's very important to check the clutch basket for notching. It doesn't take a whole lot of notching to get the plates to hang up to cause the slippage you're describing. You got almost 5 years out of a set of plates, that's great.

Those are aftermarket plates, for one thing (maybe it's just the way the plain plates look in the picture, but it looks stippled.  factory plates are smooth) .  If the slippage appears worse in higher gears than in lower, it almost certainly is the clutch.  First, though, be sure there's play in the cable. 


Use OEM Yamaha plates.

Those are aftermarket plates, for one thing (maybe it's just the way the plain plates look in the picture, but it looks stippled. factory plates are smooth) . If the slippage appears worse in higher gears than in lower, it almost certainly is the clutch. First, though, be sure there's play in the cable.

Use OEM Yamaha plates.

OEM steel plates do have the little indentions in them.

You can get the OEM clutch kits for about $120 online. Includes fibers, steel, and springs.

Grey, you are correct the plates are stippled but I dont ever remember putting in a new clutch. I think its the original.


What do you guys think the metal shavings would have been from? Seems odd that it would let go at once and turn the oil dark gray, i was worried that its more than just a clutch.  


The basket has a few grooves in it, I will take a picture and share.

Must be recent development.  The clutch I installed last year didn't have them.  But then, the '07-'09 uses different steels, too.

If you still have any of the old oil, shake it up and drag a magnet through the oil itself to see if there's a lot of iron in it.   "Some" is always normal, but a lot is a possible bad sign. 


It's fairly common with the '07-'09 clutch when ridden in tight technical stuff to have the plates heat up and expand, which adds a lot of play in the cable.  The rider may then adjust it on the fly to manage the problem, but the play goes away again after it cools down, and if he then fails to readjust it to have free travel again, it slips. 

Here is an image of the clutch basket, it has some grooves but not too deep. What do you guys think?Clutch 2014-07-23 11.57.03.jpg

Try the plates first.  Worry about the basket if it's not fixed.

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