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  1. #1

    SL750 Piston Replacement question

    First off... total noob here to the PWC scene. But I am a good mechanic and a good paint and body man as well.

    I heard someone state that a piston could be replaced without pulling the motor. Is this true and if so can someone explain it to me?

    Here is my situation:
    199x SL750 with the classic hole in the PTO piston. It's the cylinder closest to the pump. (please correct me if I'm wrong)

    The watercraft is in excellent shape and has been stored assembled for the last 5 years. If I opt to pull the motor I'm going to put it back better than stock but not too wild. Cradin Industries has offered to donate some high performance coatings to the internal components. Mainly the pistons and skirts.

    Any advice from the experts?

  2. #2
    It's super easy to replace a piston on these engines. I think a few guys have even done so while on the water.

    1. Remove the water-rail that sits on top all 3 heads.
    2. Remove the 6 cylinder head nuts, and pull the head.
    3. Remove the 4 jug nuts at the base of the jug, and pull the jug.
    4. Remove 1 of the wrist-pin C-clips. Make sure you don't drop it in the crank case!
    5. Slide the wrist-pin out of the piston. It might be a bitch to remove, depending on the condition of the piston.
    6. Drink a beer.
    7. Clean the cylinder base & crankcase and install a new gasket with RTV.
    8. Install new piston. Make sure the arrow points forward. Make sure the C-clips are seated correctly.
    9. Reverse process of removing.
    10. Depending on the condition of the head gasket, it can be reused. If it's garbage, buy a new OEM one.

    I think that about does it.

    Do you know what caused the hole in the piston? Do you know what condition the carbs are in? How does the compression check out on the other 2 cylinders? If you haven't done so already, upgrade your fuel system with new 1/4" line and triple outlet fuel pump.

    Let us know if you have any question. This is a great commodity with TONS of knowledge.

  3. #3
    Thank you for the reply! Should I be concerned about and debris down inside the motors from the burn hole? Its not that large. less than a 1/4 inch diameter

    If I decide to just replace the piston who would be a good source for a replacement OEM piston/kit?

    I'm thinking about just replacing the one piston getting it out on the water then tearing it down for a complete rebuild over the winter.

  4. #4
    Hell Bent or Heaven Sent? Bent's Avatar
    Join Date
    Jul 2007
    Pinawa, Manitoba, Canada
    I melted a hole into a piston on a Polaris Sled with a fuji engine a while ago, (frozen carbs), al the debris blew right out the exhaust ports - no grunge in the crank what-so-ever.

    I can't say if it would be the same in this case or not.

  5. #5
    thesepaperwings's Avatar
    Join Date
    May 2007
    South East Kansas
    Most of the time a holed piston doesn't get anything inteh cases. You really have to worry when a skirt breaks and the pieces fall down because they can't go out the exhaust

  6. #6
    Quote Originally Posted by thesepaperwings View Post
    You really have to worry when a skirt breaks and the pieces fall down because they can't go out the exhaust
    Tell me about it. Me breaking piston skirt=complete overhaul to my jetski. But I'm actually happy that happened now.

    As far as what piston to go with. I've always used WSM pistons and never had any problems with them. Can't beat the price and it comes with everything you need (piston, rings, wrist-pin & clips).

  7. #7
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Cleveland OH
    One thing SC forgot about, pulling the exhaust pipe off. Pretty big pain.

    Can totally change the piston while in the boat. BUT, you need to find the reason it happened first. Maybe take her all the way down and do the complete rebuild you want to do.

    These are really easy to work on if you follow the manual posted in the tech section.

    Oh, and welcome to the Hulk.

  8. #8
    Thanks Guys! Any advice on a vendor? I'm looking to upgrade the fuel pump, Install the PTO piston and replace all the hoses.

  9. #9
    I bought pistons off ebay
    Unbelievably fast shipping, never had a problem with those guys.
    Search for triple output pump on ebay too. I got fuel hoses from Autozone.
    I think SBT has carbs rebuild kits but don't buy fuel pump there - it is not triple output.
    To piston replacement - you really don't have to remove engine. When you got to the point where you are going to put the new piston in put C-ring on arrow side, put rings on the piston, then spread a little bit of oil on the piston and put it in the cylinder compressing rings with a hand. Put pin half way in and set it on the rod, push pin all the way through bearing and install second C-ring.

  10. #10
    Danke Mista!!

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