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  1. #1

    Took Heads Off My SL650, Pistons Look BAD! (W/ PICS)

    Ok, so as some of you may know... My Ski starts and idles fine, has a full carb rebuild, and yet quite often, usually when going WOT, letting off for a second, then back at it, will get awfly close to stalling, and you need to pump the choke a few times and then its just fine, with no choke at all.

    I took all the heads off today, and this is what i found... What causes THIS?


    Front Cylinder


    Front Cylinder Head


    Rear Cylinder Head (Center Looked Fine)

    All 3...

    Thanks In Advance...
    Eric


  2. #2
    Moderator beerdart's Avatar
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    Something came apart. Needle bearing piston ring etc....

  3. #3
    show the tops of the pistons! but it looks like only one is bad? so if thats the case somone ran a bad head

  4. #4
    Quote Originally Posted by ZMANN View Post
    show the tops of the pistons! but it looks like only one is bad? so if thats the case somone ran a bad head
    I would have liked to, but it appears there was no pics taken of them all, and the front one is the only one thats really bad. Its already back together. The other two look alright.

    But what should i replace here, all 3 pistons, rings, and heads? Or do the heads being like this not really matter?

    Im trying to keep this cheap, and it dosent need to be perfect. Should i go for one used piston, and new rings all around, keep the heads?

    The walls are fine on 2, and the rear has some light scoring on it, but it still had 90+psi compression, so its not a big deal if you ask me. The front cyl gets 25ish psi...

  5. #5
    Since this might be expensive anyways, What would be needed to just make this into a 750 or 780? Anyone got the parts laying around for cheap?

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by ZOMGVTEK View Post
    ...the rear has some light scoring on it, but it still had 90+psi compression, so its not a big deal if you ask me. The front cyl gets 25ish psi...
    90PSI is not enough compression.

  7. #7
    Quote Originally Posted by K447 View Post
    90PSI is not enough compression.
    Right, but i paid $300 for the ski and trailer, and it runs damn good if you pump the choke. Im just looking to get the 30ish psi into the 90+ range in hopes it would help a bit.

    But i think im just going to do a 750 swap...

  8. #8
    you may want to dbl check your psi doing the test with another gauge and throttle wide open if you did not do that! but from the pic I would at least do 2 heads 1 piston and maybe a cyl?

  9. #9
    Quote Originally Posted by ZMANN View Post
    you may want to dbl check your psi doing the test with another gauge and throttle wide open if you did not do that! but from the pic I would at least do 2 heads 1 piston and maybe a cyl?
    I did 5 or 6 compression tests, all came out the same... And the last few i did at WOT, but it didnt make a difference.

    And thats what i was thinking as well, ill wait and see when radracingpwc responds with a price for the 750 parts, and then go from there.

  10. #10
    Quote Originally Posted by ZOMGVTEK View Post
    I did 5 or 6 compression tests, all came out the same... And the last few i did at WOT, but it didnt make a difference.

    And thats what i was thinking as well, ill wait and see when radracingpwc responds with a price for the 750 parts, and then go from there.
    cool! don't forget to rejet

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