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  1. #1

    Angry Yes, another....Misfire???

    So i keep posting things on here but sorry!!! I'm gettin really anxious becuase my ski is almost running good!!!! I had it out just awhile ago, after the carb closest to the front of the boat was not getting any fuel so i fixed the needle (it was stuck shut) Finally hit over 40mph, got to run around a little bit on the river and then all of a sudden it started running like COMPLETE shit, it would not rev past 1800 rpmssssssss I also checked the reeds and they were fine!!! WHAT COULD IT BE!!! It also sounded like it was trying to misfire when i was WOT.

  2. #2
    800AMSOIL4U's Avatar
    Join Date
    Aug 2006
    Morgan Hill, CA
    Check it with new plugs. Did you roll the ski over and get water in the engine? If so I would check and see it the crank is still in index.

  3. #3
    Have never rolled it under my watch, never was fast enough....What are the best plugs for it??? How do i check the index?

  4. #4
    Lake Mead Bum & BTLS Mark starflight's Avatar
    Join Date
    May 2007
    Boulder City, NV
    Check the compression.

  5. #5
    I just did a ring job on it so i dont know how it could possibly have too low compression, unless i really screwed it up....but i can check tommroow

  6. #6
    Join Date
    Jul 2007
    Cedar Rapids,Iowa
    Just so you know something didn't really fubar and burn something. Check to make sure you don't have a kinked fuel line. PM sent.

  7. #7

    Join Date
    Jun 2008
    Bullhead City AZ.

    Checking the Index on your engine

    Hi SMX949
    How to check the index on your crank
    Take the plugs out.
    1. You will need a dial indicator bring any one of the pistons to TDC using the Dial Indicator
    2. Then check the other cylinder or cylinders if its a triple the others should be the same height in the cylinders check them with a pair of calipers they should be within .020 a max of .040 or in metric .5mm to 1.0mm any more then that your way off.
    This is the quick and easy way That I do when a boat comes in for repair that is running poorly.
    Always start with compression checks and index first it happens more often that you think and on all Polaris watercraft more then the other brands because of the way the cranks are held together in the centers.
    The best way to check index is by using a degree wheel checking all 3 cylinder starting with the front one cylinder at 0 degrees or TDC then rotate to mid should be at 120 then the rear at 240 and back to the front at 360.
    If you have a twin the other cylinder will be at 180 degrees or a BDC
    Just a few degree's can give you a world of problems. If your off its time for a crank sorry depending on what it is some people can disassemble the crank and re-index but in most cases its just shy of a total rebuild in price.
    I use for cranks and all or most machine work.
    Then start checking ever thing like Exhaust leaks, fuel leaks, water in fuel, water getting in the cylinders or engine from a bad gasket like a blown head, exhaust manifold gasket or in some watercraft a base gasket, Then if you canít find anything its time to remove carbs and go throw them slowly checking and cleaning set your POP off pressure and replace all the diaphragms.
    I have even seen on older watercraft a bad water box cause a problem a broken water baffle blocking the exhaust outlet causing it to choke it out and not get RPMís
    I hope this helps I will keep checking back for updates
    God Luck

  8. #8
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Cleveland OH
    Quote Originally Posted by starflight View Post
    Check the compression.

    It doesn't take long to burn a piston if you're running lean.

    I did mine in about 70 yards of WOT running.

    0 compression on the cyl with insufficient fuel.

  9. #9
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Quote Originally Posted by lovehavenfun View Post
    ... I have even seen on older watercraft a bad water box cause a problem a broken water baffle blocking the exhaust outlet causing it to choke it out and not get RPMís...
    Now that would have been tricky to find

    Hope it wasn't a Polaris

  10. #10
    can you tell what my psi is for a 1993 polaris 750 sl is many thanks in advance

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