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  1. #1

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    Rebuild of 15F Racing Engine-What to look for

    The engine in my STX-15F race boat needs to be completely rebuilt and I'm looking for opinions on how to approach the project. The following questions come to mind:

    1) I would like to find a local shop to do the job so I don't have to deal with shipping, etc. Can a shop that has experience with the 1.5 L Kawasaki motorcycle engine use the same approach for a PWC engine?

    2) According to the seller, this engine requires 100 octane fuel. Are different piston and bearing clearances required for a high compression platform?

    3) Are there specific components that should be replaced with heavier duty ones to ensure more durability?

    I'm not going to race the boat but I want to restore the power that it was capable of when it was built originally. If someone on this forum would like to take on the whole project, I would consider shipping the whole boat so the engine could be installed and tested also.

    Does anybody have words of wisdom?


  2. #2
    Connecticut CrazyA's Avatar
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    I don't have any 4-stroke input, but what all is done to your ski modification wise? Pics?

    EDIT: Found pics on another thread. Looks killer with the " bitchin' stitchin' "

  3. #3

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    Quote Originally Posted by CrazyA View Post
    I don't have any 4-stroke input, but what all is done to your ski modification wise? Pics?

    EDIT: Found pics on another thread. Looks killer with the " bitchin' stitchin' "
    Actually, those are pictures of my '12 STX. The engine I'm working on is in the race boat that I purchased from a forum member. It is a 2004 Kawasaki STX race hull and the engine has a 2006 build date. It is set up for closed course duty with lowered sponsons, and a Skat pump with a drop nozzle. I bought it "as is" so I'm trying to figure out what the issues are right now.

  4. #4
    OzarkYamMonster's Avatar
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    Are you sure it has any? Does it not run now ?

  5. #5
    Connecticut CrazyA's Avatar
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    Quote Originally Posted by pro1200 View Post
    Quote Originally Posted by CrazyA View Post
    I don't have any 4-stroke input, but what all is done to your ski modification wise? Pics?

    EDIT: Found pics on another thread. Looks killer with the " bitchin' stitchin' "
    Actually, those are pictures of my '12 STX. The engine I'm working on is in the race boat that I purchased from a forum member. It is a 2004 Kawasaki STX race hull and the engine has a 2006 build date. It is set up for closed course duty with lowered sponsons, and a Skat pump with a drop nozzle. I bought it "as is" so I'm trying to figure out what the issues are right now.
    Ohhhhh. Any chance of seeing some pics again then? lol... Not trying to jump on your thread. Give me the word and I will clean up my posts. Just love seeing pictures of any race machines…


  6. #6

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    Quote Originally Posted by OzarkYamMonster View Post
    Are you sure it has any? Does it not run now ?
    The seller said it had a "tick" and checked the valve clearance and it was fine. I had the clearance checked and it was fine but there is very low compression in all of the cylinders. Upon removal of the head there was a lot of oily residue noticed in the cylinders and the surface finish of the cylinder walls is poor. I would like to start fresh because I think the noise may be a loose bearing in the crank train.

  7. #7

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    Quote Originally Posted by CrazyA View Post
    Quote Originally Posted by pro1200 View Post
    Quote Originally Posted by CrazyA View Post
    I don't have any 4-stroke input, but what all is done to your ski modification wise? Pics?

    EDIT: Found pics on another thread. Looks killer with the " bitchin' stitchin' "
    Actually, those are pictures of my '12 STX. The engine I'm working on is in the race boat that I purchased from a forum member. It is a 2004 Kawasaki STX race hull and the engine has a 2006 build date. It is set up for closed course duty with lowered sponsons, and a Skat pump with a drop nozzle. I bought it "as is" so I'm trying to figure out what the issues are right now.
    Ohhhhh. Any chance of seeing some pics again then? lol... Not trying to jump on your thread. Give me the word and I will clean up my posts. Just love seeing pictures of any race machines…
    No problem! I can talk watercraft all day long-especially since it's 20 degrees here in Minneapolis.

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  8. #8
    Pain is fear leaving your body.... rlovebk's Avatar
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    Looks like Trish's old ski no? Send the crank out to APE if your not in a hurry and want very good balanced and lighter crank.
    Smart to tear it down as I bet it's worn out. That was a fast good turning 15F.

  9. #9

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    Quote Originally Posted by rlovebk View Post
    Looks like Trish's old ski no? Send the crank out to APE if your not in a hurry and want very good balanced and lighter crank.
    Smart to tear it down as I bet it's worn out. That was a fast good turning 15F.
    Yes, it is Trish's old boat. The good turning part is what I'm after. I have always had an irrational need for cornering g forces. I hadn't thought about having the crank built separately. That is a good idea and I do have all winter to do the project.

  10. #10
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    What are your goals for it?

    Sean

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