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Thread: Polaris 101

  1. #1
    blegan's Avatar
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    Polaris 101

    When my family got involved with watercraft, we had a kawi 650 at first I was intimidated bye the complexity of a 2-cycle marin engine! over the past 3 yrs. Ive pretty much become capable working on 2cyl, w/ 1 carb. Now Ive got this 94 750slt W/hole in piston. Not a problem I thought. I want to thank k447 for service manual pdf everything I need to know about this boat. I dont understand some peoples logic, engine was rebuilt less than 20 hrs.But who ever did install used the old gaskets on intake , base, exhaust. putt broken reeds back in , let fuelsystem untouched, bad fuel lines,auto cock still present, no restrictor, on & on. Dont get me wrong Im not bitchig, I actually enjoy the wrenching, & bye the time Im done Ill be proficient w/ fuji motor
    Thanks to all
    Brian
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  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    That's some serious blow-by on that piston.

    I guess I have to question the untouched fuel lines but no restrictor? It should be about 1" inside the return hose going back to the gas tank.

    With a hole in the PTO piston, you need to look for air leaks in the crank seals and also to look at the crank phase.

    If the ski was ever flipped and ingested water, the first carb to get the most water intrusion would be the PTO because it was first in line.

    It's possible that water may have hydrolocked the crank and caused the PTO to come out of time. That can lead to a timing/holed piston problem.

    Good luck with your build, and ask any Q's you have along the way. We'll help you out.

  3. #3
    blegan's Avatar
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    not for sure

    Quote Originally Posted by xlint89 View Post
    That's some serious blow-by on that piston.

    I guess I have to question the untouched fuel lines but no restrictor? It should be about 1" inside the return hose going back to the gas tank.

    With a hole in the PTO piston, you need to look for air leaks in the crank seals and also to look at the crank phase.

    If the ski was ever flipped and ingested water, the first carb to get the most water intrusion would be the PTO because it was first in line.

    It's possible that water may have hydrolocked the crank and caused the PTO to come out of time. That can lead to a timing/holed piston problem.

    Good luck with your build, and ask any Q's you have along the way. We'll help you out.
    Your right that blow by is on the severe side! When I posted this thread, I was pretty confident about why piston has a hole. The fuel lines,no restrictor,also the needle& seat on that carb was stuck shut. So I figured between a new 3 outlet mikuni fuel pump, completely rebuild all 3 carbs & fuel system from tank to pump. I thought between that & doing a leak down test cases held pressure, so Ive eliminated quite a few problems.Now the issue of crank phasing comes up.Im in a delima about the crank being indexed or just continue with reassembaly? Any ideas,?what would you do?
    Thanks Brian

  4. #4
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    I'd conduct a test on the phase before you go any further.

    Hopefully it's all good and you can continue assembly.

    If not, now is the time to address it.

    As long as the bearings are all good, you'd only need to have the crank trued. Which would be much cheaper than a rebiuilt crank. Especially if it's only the PTO that's out.

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