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  1. #1

    Polaris SL750 1993, Denmark

    Hey..
    I'm new totally new in this PWC-world and have just bought a Polaris SL750 Watercraft. The guy that i bought it from, had for about three weeks ago startet it, but the plugs was Game Over. He sat in three plugs from his car and the engine start. It run for about 10 minutes and then stops. In the #3 pistons there was a big hole. I have now bought it and want to fix it. He didn't have the space for it any longer and he sold it to me very cheap I think, 800$. I have bought Piston Kit, Complete gasket kit, Spark plugs and a supplemental fuel pump kit to add fuel delivery.
    Okay, my questions are.

    1) Could it be the use of wrong Sparks plugs from a car, that have made the hole in #3 piston???
    2) If the problem is, not enough fuel delivery, can I then fix it with the Supplemental fuel pump kit I've bought on SBTontheweb.com for 50$???
    3) Have do I instal this Fuel pump kit??? ANyone who have a diagram or something???
    4) Can I use the NGK BPR7ES spark plugs, or should I use NGK BR8ES???

    Thank you everyone who answer. I don't now anything about this engine. Sorry my english, if anyone don't understand

    Sincerely
    Rasmus, Denmark.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Vesterbye View Post
    ...just bought a Polaris SL750 Watercraft.
    The guy that I bought it from, had for about three weeks ago started it, but the plugs was Game Over. He put in three plugs from his car and the engine start. It run for about 10 minutes and then stops.

    In the #3 pistons there was a big hole.

    I have now bought it and want to fix it. He didn't have the space for it any longer and he sold it to me very cheap I think, 800$.

    I have bought Piston Kit, Complete gasket kit, Spark plugs and a supplemental fuel pump kit to add fuel delivery.
    Okay, my questions are.

    1) Could it be the use of wrong Sparks plugs from a car, that have made the hole in #3 piston???
    2) If the problem is, not enough fuel delivery, can I then fix it with the Supplemental fuel pump kit I've bought on SBTontheweb.com for 50$???
    3) How do I install this Fuel pump kit??? Anyone who have a diagram or something???
    4) Can I use the NGK BPR7ES spark plugs, or should I use NGK BR8ES???

    Thank you everyone who answer. I don't now anything about this engine. Sorry my english, if anyone don't understand

    Sincerely
    Rasmus, Denmark.
    Welcome to the Green Hulk!
    For Polaris PWC info and support, this is the place.

    English not a problem, quite understandable.

    What model year is your SL750?
    The last two digits of the HIN number on the metal plate (located on the hull rear deck) is the model year.

    1) Wrong spark plugs might have contributed, but I think the main problem was too little fuel being delivered to the cylinder during high speed operation.

    2) It seems you have been studying here, so you know about the original single output fuel pumps getting weak with time. You should also replace all the fuel lines, including those inside the fuel tank, as the original fuel hoses go bad over time.

    Dis-assemble and clean up the fuel selector switch. If the O-rings inside are bad, it will allow air to leak INTO the fuel lines during operation. The air bubbles reduce the amount of fuel available to the engine, and can cause lean cylinder operation = burned piston.

    Also, take the carburetors apart, and clean the internal fuel filter screens. Better yet, rebuild the carbs. You can purchase rebuild kits, including from some Green Hulk members. If the carb screens are clogged, or the carbs internally are gummy with old gasoline residue, it can cause problems.

    If your SL750 still has the auto-cock device installed in the fuel line at the pump, it should be removed. They tended to fail, and cause problems.

    3) The SBT triple outlet fuel pump might come with installation instructions. If you still need more information, just ask us.

    Even better, do some searches on Green Hulk Polaris. There are diagrams and thread posts regarding the installation of triple outlet fuel pumps.

    Try to keep the pulse hose from the crank case short (under 30cm), but also be sure the fuel pump is mounted above the pulse fitting on the crank case, and the hose does not droop down. This keeps any liquid oil/gasoline in the crank case from getting into the pulse line or the fuel pump.

    4) Use the correct, exact spark plug recommended by Polaris for your engine. Unless the engine has been modified for more power, the recommended NGK spark plug is the one to use.

    If you have not done so already, download the 1992-1998 Service manual.

    Often, a few clear photos can help us see what your problem is. When replying to a message, scroll down to the Manage Attachments button to add pictures to your post.
    Last edited by K447; 04-28-2008 at 09:57 PM.

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk. This may help you with the install of the fuel pump. http://www.greenhulk.net/forums/showthread.php?t=15433

    A good possibility of the hole being burned could be an air leak or out of index crankshaft also. Please search for a "leak down test" and crank indexing. You can perform simple tests to rule these out as possible causes.

  4. #4
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    The plugs from the car could very well have smoked the piston,a extended tip plug or alot hotter range would put the burn to close to the dome of the piston.I would check everything first as suggested so you don't hole another piston,then you'll feel safe after the rebuild.

  5. #5
    Supplemental pump, is OK. Most use the 3 outlet Mikuni Fuel Pump.
    kit available at www.jetskimechanic.com


    While the engine is out , you might consider going pre-mix (SBT) has the oil ratios and most important the engine break-in procedures.

    My oil lines fell off, flooded the hull with oil, what a mess.

    Then, use BPR8ES plugs.

    Additionally, check the pump for rotation. and The impeller to housing clearance.

    Pull the rear cone to see if water and or corrosion is there. Then re-bearing and re-seal as required.

    It is important to keep the shaft mid bearing contraption lubed as well as the zerk at the engine coupler. You can just replace the seals inside(the mid bearing housing) with out replacing the entire unit

    Cheers !!

  6. #6
    First of all, thanks for all your answer. It's a lot more complicated than it seems like I see

    1) The watercraft is from 1993.
    2) The watercraft, is already pre-mixed

    3) Why should I use the BPR8ES spark plugs? I've already bought the BPR7ES. Originally Polaris suggest to use BR8ES. Is it something to do with the pre-mix or?

    4) Where is the fuel selctor switch?

    5) A rebuild kit for the carbs, what is that? I mean, what is the meaning with it?

    6) What is Auto-cock?

    I will soon post some pictures!

    Thank you.

  7. #7
    The BPR8ES are colder and suggested due to the pre mix.
    Selector sw switches between normal and reserve fuel pickups.
    Auto cock thing that was supposed to turn off fuel , mtd by the fuel pump. May be there and may not be there.
    Purchase a Clymer manual, lots of pictures
    SBT has carb kits and instructiuons for rebuilding(diaphrams, filters ,gaskets) on their web site.
    www.partsland.com has on line parts pictures, part numbers and prices.

    Cheers !!!

  8. #8
    Moderator beerdart's Avatar
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    The factory Polaris manual can be found here..
    http://www.greenhulk.net/forums/showthread.php?t=38870

  9. #9
    ph2ocraft's Avatar
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    Sometime it doesn't pay to go cheap, carbs are one of those times.
    If you're going to get kits for your carbs don't get the crappy aftermarket stuff like SBT sells, we see problems with those kits all the time.
    You don't need to buy the entire kit either, just purchase what you need.
    Randy at Watcon and John at Jet Ski Solutions sell the original equipment replacement parts individually.

  10. #10
    ...ditto !!!

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