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  1. #1

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    Slt 750 problems

    Well heres the story, i was on pwctoday and they recomended me to come here. I have a slt750 just bough it a month ago. First thing i did was add the extra fuel pump from sbt, changed fuel lines, and a new battery. I rode it before i bought it and it ran like my other one. When i rode it the second time it knocked a hole in the mag piston. The guys on pwc said it could have knocked the crank index out of phase. But others said that i could replace the piston and cylinder. My question is, is it ok to clean the carbs and re-use them, or do i need to get the 780 carbs?


  2. #2
    Moderator beerdart's Avatar
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    Welcome to the Hulk..

    You should verify crank index. The 780 carbs are the same with different jets.

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome to the Hulk!

    This is the best place on the web for Polaris PWC support.

    Click here for the Polaris Service Manuals.

  4. #4
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Welcome to the Hulk!
    You may not need a new cylinder. Depends on wether it was damaged or not. Also if the cyl-piston clearance is within tolerence and no damage, I'd re-use it. Just get a piston, hone the cyl and let it ride. It would be wise to check the index before doing anything.
    What do you mean you installed an additional pump? Added one to the existing pump? How was the pulse line done?
    We have been discussing the 750- 780 carb swap. I think it is a bunch of crap. I can't see the high spd passages swelling shut, and the 780 carbs are the fix. They are the same carbs, just turned around. You can read what has been said in this -> thread. Rebuild- clean the carbs you have and you will be fine. It would also be wise to leak check your engine to make sure its not running lean from an air leak.

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by beerdart View Post
    ...You should verify crank index.

    The 780 carbs are the same with different jets.
    You will find a lot of useful info on these forums.

    Use the Search function, and spend some time reading threads from other owners with similar models.

    There are several threads describing how to check crank index. It isn't that hard, and you do not need to remove the cylinder heads to do the check.

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk cdieter.

    Remove the autocock if you still have it installed.

    Ditch the SBT fuel pump garbage and get a Mikuni triple outlet fuel pump. They're about $28 now.

    Make sure you have the fuel restrictor inside the return hose if you replaced the lines already.

    You can install a new piston if the cyl is fine. A single WSM piston kit can be had for $73 on Ebay, includes everything but gaskets.

    Thoroughly clean or rebuild your carbs.

    Also clean/inspect the fuel selector valve. (petcock)

    Should get you back in business for minimal $$$$.

  7. #7

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    Thanks guys

    Well thanks for all the help. I bought the kit from SBT and routed the hoses like the instructions say. Have any of you heard how good this pump is? Is there any way i can test the pump to be sure its good? its the single outlet and i am running the front cylinder by itself. O and what is the autocock, xlint89? i have no idea. And the guy that i bought the ski from replaced the lines, where is the fuel restrictor on the return line? what does it look like? and if its not there what will it do without it? Thanks

  8. #8
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    If you burn't a hole in the mag piston with a pump feeding it all by itself, you have other issues. Have the carbs been gone through and cleaned up? The internal filter in the carbs been cleaned?. If all thats ok, you may have an air leak causing that cylinder to run lean.
    Can you scan and post those instructions?

    I'd only run the triple outlet pump. The fuel line restrictor should be in the return line near the carbs, and held in place with a zip tie or clamp.

    The auto cock is item #4 in the image...
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  9. #9

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    no restrictor

    Well i guess the guy didnt replace the fuel restrictor cuz there aint one there. and the carbs are clean, the little clear filters inside them are clean. When i bought the jet ski i rode it for probably 10 minutes and it ran good the whole time, 42 mph, but bogged slightly when i really got on the throttle. the guy told me it was because the gas was a year old. which made sense to me. before i rode it again i added the extra fuel pump and rode it only for 20 minutes cuz it was cold as heck. when i got home i started it to get the water out and it would not start. thats when i saw the hole in the mag piston. so thats the story, all the help is great, like i said earlier, is there any way to test my routing of fuel lines and test the new fuel pump?

    Thanks

  10. #10
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by cdieter View Post
    ...is there any way to test my routing of fuel lines and test the new fuel pump?...
    Once you get a replacement return line fuel restrictor installed, you can tee a fuel pressure gauge between the carb exit and the restrictor.

    Normal fuel pressure is circa 2PSI at idle, and around 4PSI at WOT.

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