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  1. #1

    New to skis need help.

    I've got a 93 SL650, and I've got some big problems. I'm new to skis, never messed with them before.

    I've got a problem with cylinder 3 (the far rear cylinder) Ran the ski for a while and ended up burning a hole in the piston.

    So for what I gather from reading here is:

    - I need to get a new 3-outlet fuel pump. (where can I get one?)
    - I think I'm going to do away with the oil injection. (I like keeping my mind at ease)
    - Sounds like I should do a leak down test, is there anywhere that has instructions on this?

    Thanks for the help.


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk CF.

    John Zigler has the triple outlet pump. (member here)

    Then download the manual in the tech section and follow the instructions for testing in it.

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

    Unless the oil pump is giving you trouble, you probably don't need to worry about it. They are fairly reliable, just make sure the oil hoses are in good shape, and change the in-line oil filter if your model has one.

    Service manual is here.

  4. #4
    Thanks for the quick responses.

    What would cause a hole in the piston on the 3rd cylinder? Everything I have read here says that your most likely to burn a hole in the 1st one at the front of the ski.

    I'll check the oil pump and see whats going on there. I know that this ski has sat for a long time before I got ahold of it. I'll check the oil lines and so forth.

    I've got a service manual for it, though it doesn't really say much about what I want to look up. I'll download that manual in the link and see what I can find there.

    What is Johns name on here? Is it just John Zigler, or does he go by something else?
    Last edited by CalledFollower; 07-24-2008 at 09:49 AM.

  5. #5
    Moderator beerdart's Avatar
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  6. #6
    What do I need to do about the piston? Can I swap it out with a new one? and where can I get a new piston?

    I e-mailed John about the fuel pump.
    I'm going to do a leak down test
    I'm going to totally go through the fuel system and make sue everything is clean before this hits the water.

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by CalledFollower View Post
    ...93 SL650...cylinder 3 (the far rear cylinder)...hole in the piston...
    Number one most popular reason for burning a hole in a piston is fuel starvation to that cylinder.

    If the fuel pump is weak, than all carbs get less fuel than they should, but typically the MAG (front) carb gets the least fuel flow, since it is the last carb in the line from the fuel pump. So the MAG (front) piston often melts first.

    BUT, if any of the carbs is gummed up and/or incorrectly adjusted, that cylinder can and will burn the piston.

    If you burned the PTO (rear) piston, then at least the PTO carb needs to be cleaned up. If one carb is not clean, chances are that all three carbs need cleaning.

    John Zigler may be able set you up with a new piston.

    If you want or need a genuine Polaris piston, there are several reputable places that get good reviews around here;
    www.watcon.com
    www.atlanticpowersports.com
    and I'm drawing a blank, but there is also...

    What size (diameter) piston you need will depend on whether the cylinder walls have been damaged enough to require boring out to the next size up (in 0.25mm increments). Most decent machine/engine shops have the equipment and knowledge to tell whether boring is required, and how much bigger it needs to go to be smooth again.

    If the cylinder is still in good enough shape without boring, the cylinder walls can be gently roughened with a hone tool (cylinder off the engine), and then a replacement piston of the correct size (same as was burned) can be installed, along with matching new piston rings, and new wrist pin, cir-clips and roller bearings for the crank rod end.

    While the new piston can be installed without further tearing the motor down, there is the question of where the melted metal particles from that hole in the piston went. Some of that metal can end up down in the crank case, where it can cause problems after you start using your repaired engine.

    If you are feeling lucky, you can just repair that one piston and cylinder, clean up ALL the carbs and the fuel system, bolt it all back together, and hope that nothing bad comes up from the bottom of the engine.

    If you want to be 100% certain that the bottom end is 100% good, that is a lot more work, as you need to pull the engine out, take it completely apart, then clean and inspect the crank case and crank shaft.

  8. #8
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    You may have a crank seal leaking also. That will cause a lean condition and burn a hole. Or crank can be out of index as well.

    Just a couple things to look into before you replace the piston. Otherwise it will burn another one. You need to find the issue and remedy it.

  9. #9
    K447, thanks for the great info.

    I'm planning on doing a leak down test, to see if there is any kind of leak in the cases.

    The whole crank index has me boggled. I read the 'hillbilly" way of doing to, but don't quite understand it.

  10. #10
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by CalledFollower View Post
    ... The whole crank index has me boggled.
    I read the 'hillbilly" way of doing to, but don't quite understand it.
    The idea is that when the MAG piston is at exact TDC (Top Dead Center), the other two pistons should be exactly, equally positioned down inside their cylinders.

    So you position the MAG at TDC then measure, using a 'stick' through the spark plug holes, how far down each of the other two pistons is. The more exact you can measure, the better.

    If the 'stick' is a precision dial indicator, all the better.

    You get the MAG piston to TDC by inserting a stick (pencil, or dial indicator) in the MAG spark plug hole, and watching for max rise of the piston as you turn the drive shaft coupler by hand.

    The degree wheel method positions each piston in turn at TDC, and measures how many degrees of rotation there is between each piston's TDC.

    Either way, you are confirming that all three pistons are equally spaced around the 360 degrees of a full crank shaft rotation. If they are not equally spaced, then the crank shaft has been 'twisted', and needs to come out and be rebuilt at a shop.

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