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  1. #1
    wreckmaster's Avatar
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    Question 93 sl750 cylinder base gasket?

    Hello,nice2meetcha.Replacing a fried piston on a 93sl750 and while scraping off the old what i assume to be original base gasket i noticed it restricted water flow whereas the new gasket is opened up completely, i'm sure it must be a improvement over the original cause it seems to be a perfect fit.My motor is the Fuji type are the base gaskets the same for both models? looking around here i appear to be a wannabe thanks!


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by wreckmaster View Post
    Hello, nice2meetcha.
    Replacing a fried piston on a 93 SL750 and while scraping off the old what I assume to be original base gasket i noticed it restricted water flow whereas the new gasket is opened up completely,
    I'm sure it must be a improvement over the original cause it seems to be a perfect fit.
    My motor is the Fuji type are the base gaskets the same for both models?
    looking around here I appear to be a wannabe thanks!
    We all start somewhere!
    Welcome to the Hulk!

    Both models? What do you mean?

    I presume you have downloaded the 1992-1998 Service manual.

    You need to ensure that whatever killed the piston is fixed.

    On the Polaris Fuji models, usually the entire fuel system needs to be checked. Fuel hoses replaced (including inside the tank), fuel line filters checked or replaced (including those inside the carbs), and carbs cleaned or rebuilt.

    The fuel selector also needs to be checked/cleaned/lubed (maybe new o-rings) to ensure it is not leaking air into the fuel lines at speed (which can cause a lean condition).

    Often the single outlet original fuel pump gets tired, and leans out the engine at WOT, especially the MAG cylinder. Typically, the fuel pump is replaced with a triple outlet version, and plumbed directly to each carb.

    If the fuel line auto-cock is still present near the fuel pump, it should be removed and discarded.

    The fuel system must be 100% good, or the engine will not run right, and will not run reliably for very long.

    Another common issue is the plug wires. You might want to remove the spark plug caps, and trim 1/4 inch from the wires, then put the caps back, with a new zip tie. Ensures a reliable and consistent spark.

    There are some other common Fuji things to check or update, but I don't recall them at the moment.

  3. #3
    wreckmaster's Avatar
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    Fuji or Domestic

    Wow that was quick!..oops i thought there was a fuji 750 and a domestic 750 i see in the bible that the fugees are 650 750 780 and the domestic ones are700 900 1050...so i guess the new basegasket is just a improved design.About the fuel lines,mabye i should have mentioned that i took the motor out and put it in a 11 ft jet boat so a lot of that got discarded,i had to replace the tank too but i made sure to put a fuel return back in the new tank i just read about the newer pump and as soon as i figure out how to get one i will.The first coupler i made to mesh the motor to a berkly minijet created serious vibrations but was so much fun i used it anyhoo mabye that fried the piston? it was the closest one to the coupler. I have a much better one now with a rubber piece similar to a lot of watercraft.I have more questions than answers I hope killing the jetski isn't a sin here it waas one of those hot pink ones.

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by wreckmaster View Post
    ...I took the motor out and put it in a 11 ft jet boat ...
    We want photos!

    Show us what you have created!

  5. #5
    Where are the other fuel-filters??? I have found them inside the carbs. but are there others, where??

    And where is the fuel selector switch I should clean?? Can't find it!!!

    Thanks...

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Vesterbye View Post
    Where are the other fuel-filters??? I have found them inside the carbs. but are there others, where??

    And where is the fuel selector switch I should clean?? Can't find it!!!
    Fuel filter, if someone has not removed it, should be near the fuel tank.

    There may also be a fuel-water separator mounted near the fuel tank, in-line with the fuel feed to the selector valve. It has glass bowl, and a red ring float inside. If the ring is floating up, not sitting on the bottom inside the bowl, then there is water in the fuel.

    The black fuel selector knob should be on the dash in front of the seat, near the steering, OR on the right side of the upper deck. On-Off-Reserve selections on the label.

    Check the 1992-1998 Service Manual, page 3.8

  7. #7
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the board Wreck. I think the 92 and 93's did have different base gasket part numbers from the 94 and newer. Those 2 years had a different cooling set up. They had cooling water flowing through the block, where 94 and newer eliminated that. You should be OK with the newer style gasket.

    As for the PTO (last cyl) burning down, most likely causes are a leaky crank seal, or since you added fuel lines, maybe the fuel restrictor is missing now. Some years used a restrictor in the return line to provide fuel pressure at WOT.

    Conduct a leak down test to see if your crank seals are bad. And install a fuel pressure gauge in the return hose. You should have about 5-6 psi at WOT.

  8. #8
    wreckmaster's Avatar
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    Quote Originally Posted by xlint89 View Post
    Welcome to the board Wreck. I think the 92 and 93's did have different base gasket part numbers from the 94 and newer. Those 2 years had a different cooling set up. They had cooling water flowing through the block, where 94 and newer eliminated that. You should be OK with the newer style gasket.

    As for the PTO (last cyl) burning down, most likely causes are a leaky crank seal, or since you added fuel lines, maybe the fuel restrictor is missing now. Some years used a restrictor in the return line to provide fuel pressure at WOT.

    Conduct a leak down test to see if your crank seals are bad. And install a fuel pressure gauge in the return hose. You should have about 5-6 psi at WOT.
    Thanks for the useful info,i dont have the restrictor,i just put a one way valve on the return,i will get a fuel pressure gauge and check it.I am not familier with a leak down test,can it be explained in 50 words or less?

  9. #9
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    For a leak down test ya wanna block off the exhaust and intake. You can use the pulse nipple to pressurize the engine for the test. Use no more than 10 psi to look for leaks. I think I used 8#s.
    The return line restrictor is a 55 jet on my 44mm carbs. I'll go look in a bit to see what it is on my 38's.
    Last edited by starflight; 05-10-2008 at 08:29 AM.

  10. #10
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Like Star said, block off intake and exhaust openings air tight. Then apply 9 psi of vacuum or psi to the pulse fitting on the block. It should hold that pressure for 3-5 mins. If it, doesn't you have an air leak and next to remedy it. Soapy water in a spray bottle helps located leaks. Most common spots are crank seals and intake gaskets. Also check head and base gaskets too.

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