03 660 Sudden Engine Noise
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Thread: 03 660 Sudden Engine Noise

  1. #1
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    03 660 Sudden Engine Noise

    New to the forum!
    I bought a 2003 660 Raptor late last year. It is in VERY VERY nice condition, very low hours. The only issue it had was some minor blue smoke on start up, which I diagnosed as valve seals. I tore the engine down (I am very meticulous) and replaced the valve seals and 3 valves (the valves seemed a little worn, lapped new ones in). While I was in their I measured the stock piston and cylinder.. both were well within spec. So for good measures I just installed some new rings. I put everything back together and also installed a Stage I hotcam. The smoke disappeared (like I expected) and the motor purred like a kitten (and ran like a raped ape).
    Other mods include full exhaust (new) and dynojet kit with airbox mod.
    Fast forward about 30-45 mins of riding.. total.. (gentle riding) and all of a sudden I get motor noise. It went from dead quiet to a knocking sound in 2 seconds. The sound goes up/down with revs. It's hard to pinpoint the source.. sometimes it sounds like top end (valves) and other times it sounds like mid/bottom end. It's not too deep, not to high pitched either. The cam chain and tensioner were well within spec and it great shape (less than 1/2 out).
    Bike runs great but is now noisy. Again, it went from quiet.. to instant and constant noise. I'm a little puzzled on what could of happened so quickly and under such gentle riding that now makes it knock. One a scale of 1-10, 10 being about to explode and 1 being slight valve noise.. I'd say it's about a 5. Certainly doesn't sound great.
    Thoughts?
    Thanks

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    Its hard to tell. It could be so many things. I would start at the chain tensioner. Maybe you did not tighten everything down? I wonder if it somehow has an oil blockage. Might be time to tear it apart again.

    Coop we miss you brother..

  3. #3
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    Ok, so I've got it torn down. Cam chain tensioner and chain well within spec (less than 1/2 out). Piston, rings, cylinder all within spec and great looking. Valvetrain looks great.. absolutely NO play in crank and wrist pin. I can't see anything engine-wise that would cause this. I've got a buddy that came over (a lot of engine experience) and we are struggling to see what could be causing this issue? Obviously something changed instantly, but we can't find a smoking gun!!

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    That may say that maybe its starving for oil. Did you check the oil screen on the bottom of the oil tank on the front of the bike? On the 660 I think there is also a screen in the case. Cant remember for sure. Did it sheer the oil pump gear, its just plastic.

    Coop we miss you brother..

  6. #5
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    One way starter clutch bearing? Makes an evil noise when its goin bad.. been there done that.

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    Good call!

    Coop we miss you brother..

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