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Thread: Ist Jet Ski

  1. #1

    Join Date
    Aug 2011
    Location
    Dyersburg Tn
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    Ist Jet Ski

    Hello all

    I just recently bought a 93 750 ss that needs some work. I know that it needs to be bored and needs new pistons, and possibly a head. I have never owned a jet ski before but have ridden other peoples some. Im probably gonna try and get it running and ride it for a while. Then i plan on doing a jetjon setup with it for river running. Does anybody have any suggestions or things to look for in the teardown that might be potential problems. Thanks in advance.
    below is a link to my photo album on the project.

    http://www.facebook.com/media/set/?s...8228e60&type=1


  2. #2
    Pain is fear leaving your body.... rlovebk's Avatar
    Join Date
    Aug 2008
    Location
    So. Cal.
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    5,206
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    Hi.

    Go thru entire fuel system and make sure lines/tank/seperator are all clean. Also pull the fuel lines from the pick-up on the tank and pull the pick-up. This has a chrome plate on plastic stuff and usually has the return hole and other stuff plugged or in a bad way. Clean it all up and put it back together.
    Also on the front left side you may have a little pull up thing with a knob on it looks almost like a choke lever. This is to let water out of the crank. It could leak air into crank area and cause a lean issue and there is a kit to plug this thing up. For parts try a guy named John Zigler. He is honest and responsive/reasonable.
    www.rockcountyjetski.webs.com
    [email protected]

    Rebuild your carb/s and torque all fittings to the proper specs. Also check your impeller for proper clearance/tolerance. Get a service manual. Has all the info you need.
    Good luck. Any questions/etc. I can try to help.

  3. #3
    Jared of Oklahoma
    Join Date
    Aug 2007
    Location
    Oklahoma City
    Posts
    386
    Quote Originally Posted by JonDoo View Post
    Hello all

    I just recently bought a 93 750 ss that needs some work. I know that it needs to be bored and needs new pistons, and possibly a head. I have never owned a jet ski before but have ridden other peoples some. Im probably gonna try and get it running and ride it for a while. Then i plan on doing a jetjon setup with it for river running. Does anybody have any suggestions or things to look for in the teardown that might be potential problems. Thanks in advance.
    below is a link to my photo album on the project.

    http://www.facebook.com/media/set/?s...8228e60&type=1
    My question is this-How do you know it needs to be bored? Is the head cracked or something? You can usually clean up the head and reuse it unless it is cracked somewhere. What about the crank? Have you checked it to make sure the bearings all spin freely and the rods are in good shape and move ok? Usually the crank it what I always seem to find bad on motors of the skis I buy to fix up. Unless you have a really scored up cylinder or even both are really bad, you can usually hone them out and go on down the road. Unless your just itching to spend money clean up your old pistons with a scotch Brits pad, and use extra care to clean in the groove where the rings go and then you may be able to reuse them. That is of course if your cylinders look ok. Don't always take the sellers word that a motor needs certain things.

    First of all as you are taking the motor apart bag all your hardware and label in plastic bags according to what they go to. For instance the head in most instances have the silver acorn nuts that fasten it to the cylinders, clean these and then bag them and then mark the bag w a sharpie pen and then zip tie the bag to the head. Next carefully remove the metal gasket in case you want to reuse it. At this point you may have to pour some motor oil down in the cylinders if they don't slide off the pistons easily. I have had some motors literally have to sit and soak up the oil for a few days before the cylinders slid off the pistons. When you get to this point you will be able to see where you stand with your crank. If the crank is bad you may just want to find a good used motor because a crank rebuild can be pretty expensive. However there are many good people here on Greenhulk who sometimes have used cranks. I have probably told you allot you already know, but if not hopefully this little bit of info helps.

    Good luck

  4. #4

    Join Date
    Aug 2011
    Location
    Dyersburg Tn
    Posts
    4
    Thanks for the info. The motor has quite a few deep scores in the cylinder walls and the rings are in pieces which are now welded to the top of the pistons. The head also has pieces of the rings embedded in it. The motor is not locked up and turns over, but i have not pulled the pistons yet. I removed the head before purchasing it and thats how i knew it would need boring.

  5. #5

    Join Date
    Aug 2011
    Location
    Dyersburg Tn
    Posts
    4
    Quote Originally Posted by rlovebk View Post
    Hi.

    Go thru entire fuel system and make sure lines/tank/seperator are all clean. Also pull the fuel lines from the pick-up on the tank and pull the pick-up. This has a chrome plate on plastic stuff and usually has the return hole and other stuff plugged or in a bad way. Clean it all up and put it back together.
    Also on the front left side you may have a little pull up thing with a knob on it looks almost like a choke lever. This is to let water out of the crank. It could leak air into crank area and cause a lean issue and there is a kit to plug this thing up. For parts try a guy named John Zigler. He is honest and responsive/reasonable.
    www.rockcountyjetski.webs.com
    [email protected]

    Rebuild your carb/s and torque all fittings to the proper specs. Also check your impeller for proper clearance/tolerance. Get a service manual. Has all the info you need.
    Good luck. Any questions/etc. I can try to help.

    Is the "choke looking thing" located on the side of the crank case?

  6. #6

    Join Date
    Aug 2011
    Location
    Dyersburg Tn
    Posts
    4
    Quote Originally Posted by jarcynvicnchris93 View Post
    My question is this-How do you know it needs to be bored? Is the head cracked or something? You can usually clean up the head and reuse it unless it is cracked somewhere. What about the crank? Have you checked it to make sure the bearings all spin freely and the rods are in good shape and move ok? Usually the crank it what I always seem to find bad on motors of the skis I buy to fix up. Unless you have a really scored up cylinder or even both are really bad, you can usually hone them out and go on down the road. Unless your just itching to spend money clean up your old pistons with a scotch Brits pad, and use extra care to clean in the groove where the rings go and then you may be able to reuse them. That is of course if your cylinders look ok. Don't always take the sellers word that a motor needs certain things.

    First of all as you are taking the motor apart bag all your hardware and label in plastic bags according to what they go to. For instance the head in most instances have the silver acorn nuts that fasten it to the cylinders, clean these and then bag them and then mark the bag w a sharpie pen and then zip tie the bag to the head. Next carefully remove the metal gasket in case you want to reuse it. At this point you may have to pour some motor oil down in the cylinders if they don't slide off the pistons easily. I have had some motors literally have to sit and soak up the oil for a few days before the cylinders slid off the pistons. When you get to this point you will be able to see where you stand with your crank. If the crank is bad you may just want to find a good used motor because a crank rebuild can be pretty expensive. However there are many good people here on Greenhulk who sometimes have used cranks. I have probably told you allot you already know, but if not hopefully this little bit of info helps.

    Good luck
    How much can be honed before the stock size pistons will have too much clearance? I have heard that too much clearance can cause the piston skirts to wear quickly.

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