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  1. #1

    90' 650sx turns over won't fire

    Ski has been sitting for about 4 years, cleaned fuel lines, tank carb, replaced battery, has spark (enough i dont know?), turns and turns but wont fire? Any Ideas? Seems like people have seen this problem before with these skis, I have seen lots of ideas but nobody saying theyve got one goin? Thanks for any help!


  2. #2
    seaobin's Avatar
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    what is the battery voltage when cranking.

    try taking a water bottle (empty, and dry) fill with oil goas mix at 40:1 push a push pin through the top and use this to drip/spray gas into the carb.

    can you get it to start if you prime this way?

    Have you checked your plugs and plug gap?

    are you getting any kind of detonation?

  3. #3
    seaobin's Avatar
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    what is cylinder compression. what carbs do you have

    1 vs 2 carbs
    \
    pics please

  4. #4
    It has a 34mm keihn carb (single) compression is at 140 on both, I cracked open the cover on the magneto and stator to find water inside... Im thinking this could be causing a weak spark causing it not to fire? sound correct? .....thanks (ill send pics soon)

  5. #5
    DPeteLand PeteSkeet's Avatar
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    Quote Originally Posted by Kolio View Post
    Ski has been sitting for about 4 years, cleaned fuel lines, tank carb, replaced battery, has spark (enough i dont know?), turns and turns but wont fire? Any Ideas? Seems like people have seen this problem before with these skis, I have seen lots of ideas but nobody saying theyve got one goin? Thanks for any help!


    yes i have... do a leak down test... seems like you are sucking in air from somewhere... lower end leak... or your piston rings...


    ig get a cheap leakdown test kid... possilby harbor freight i saw one adv. last week for like $20

    hope that helps!

    (ive owned a few 650's and if you still have the stock drain plug for the pistons to release oil... id start there... those are a nusence and when the start pulling air.. and there is water in the engine bay area... say bye bye to your ski once it begins to set and turn the gas and oil to a light orange mayo...

  6. #6
    DPeteLand PeteSkeet's Avatar
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    thats saying you have decent park and the motor is turning over as it should... other wise everyone else is correct... the flywheel or stator when bad... causing weak to little spark.... this is common to see a stator go bad or the magnets die in a flywheel.... although i feel thats not your problem


    one of the many things my father taught me (being an engineer and working on two stroke motors when he was younger for 15 years) was a story of when he was working on a motorcycle...

    completely rebuilt... perfect condition.... except for one bottom end gasket.. he tried to start it for hours... nada... did a leak down test and found the problem was the gasket... changed it out.. barely hit the start and that motorcyle fired like a screaming banshee.


    i cant say 100% whats wrong witht he ski... anthing is possibly.. even that your carb isnt delivering enough or too much fuel. this was the problem in a friends 550 (both the gasket and the carb) but i can say if i had a good guess from what you are telling me... your problem is a bottom end leak.. its up to you to find it.


    good luck im sure youll fix it!

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