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  1. #1
    brav's Avatar
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    Material from hole in piston

    Hello all. New to this great source of info. Probably spent more time reading this forum then working on the ski.
    Iíve now got a í94 SL750 been sitting around unused in a buddies field for a couple of years. My problem is a hole in piston 1. After reading a bunch of threads I performed a crank index check, allís good there. Took the dome and cylinder off and found both in good shape other then a little bit of rust. (That was fun. Should have read Lockoutís first machine thread first). From my noob experience (schooled by Hulk), looks a tad lean.



    Question is about the material from the piston hole. Is it enough to inspect the crank area from the top (with cylinder removed)? Or is it necessary to remove engine from hull and open crank area? Can the crank bearings get contaminated with piston material? I would think an unfortunate yes. If so, can I inspect the crank bearings, or are they sealed?

    Things to do: hone cylinder 1, check the other two pistons and cylinders, check fuel system
    Parts I assume I need: piston (and parts), gasket set, a triple outlet fuel pump

    Thanks for any and all help.


  2. #2
    it is possible for the piston material to find it's way to the crank but more likely it went out the exhaust , when u pull the cyl you can look around

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
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    Redo the fuel system (new hoses, etc), as per the other threads I am sure you have read, and clean those carbs.

    Don't lose track of the fuel restrictor part inside the return fuel line. Not all early Fuji models had one, but if yours does, don't forget about it.

    The triple fuel pump will only help when the carbs are in good shape internally.

  4. #4
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk Brav.

    If the ski sat for a few years, try turning the crank over by hand with the spark plugs removed. It's possible the crank is rusted already which would need a rebuild of the entire bottom end. No need wasting $$$ on top end if the bottom is toast.

  5. #5
    I like Boobs. wetwolf's Avatar
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    Quote Originally Posted by xlint89 View Post
    Welcome to the Hulk Brav.

    If the ski sat for a few years, try turning the crank over by hand with the spark plugs removed. It's possible the crank is rusted already which would need a rebuild of the entire bottom end. No need wasting $$$ on top end if the bottom is toast.
    +1, that crank will grenade and take out your shiny new top end

  6. #6
    brav's Avatar
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    Thanks all for the replies.

    When I turn the crank by hand, I don't feel any resistance that I would attribute to rust. Just the normal sucking/blowing sound/resistance that I would think is the air rushing in from the crank to cylinder.

    What I did find under the mag piston, just on top of the crank area, are sand size grains of metal. I'm guessing there's more down under. I get to pull the engine, eh? And I get to see if there is rust in the other two crank areas. Canít wait. Sounds fun. One of the things I worry about is lining the drive shaft when I put the motor back in. So do I just wash out the area? Inspect bearings? Or just replace the lot? I understand thatís a bit expensive. Or I could leave the motor in, wash the crank area out with heavier then metal fluid and be done.

    I traced the return fuel line and find no evidence of the restrictor. Not even a bump. The fit must be perfect if I have one. Thanks for the advise, I will search for it.

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by brav View Post
    ...I traced the return fuel line and find no evidence of the restrictor. Not even a bump. The fit must be perfect if I have one. Thanks for the advise, I will search for it.
    I think there was usually a clamp around the outside of the hose where the restrictor was located, to keep it in place.

  8. #8
    Feral's Avatar
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    Quote Originally Posted by K447 View Post
    I think there was usually a clamp around the outside of the hose where the restrictor was located, to keep it in place.
    They also use Plastic Wire tie/Zipties to hold them in place usually located within an inch or two from the fuel return barb on the return line

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    If you're seeing metal flakes, I'd say pull the engine for a thorough inspection of the crank. Besides, you can properly clean the cases out as well. Maybe install an oil pump block off plate too at this time.

    Remove the carbs and clean/inspect them as well. Good time to inspect/replace reeds, etc....

  10. #10
    brav's Avatar
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    Oil pump block - had to look that one up. What I didn't find was why. I'm guessing to take a potential failing part off the boat. Pre-mix instead. Works for me.

    Pulling motor and going through the list of checks.

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