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  1. #1

    Exit Nozzle Boring

    Found a very easy and accurate method of boring out the 85mm nozzle to any size you desire. For anyone who has access to an engine cylinder ridge reamer, and a cylinder flex hone, and vernier calipers its a cake walk. The beautiful thing is, you can cut the nozzle in .2mm increments if you want to fine tune to an exact rpm you are shooting for, and at the same time, add some holeshot into your boat. All you have to remove from the pump is the steering nozzle, and nothing else to make the cuts. You also end up with a highly polished, perfectly concentric diameter exit nozzle of your choice. Youll find the factory exit diameter is far from concentric also.
    For those that dont have these tools, a flex ball hone is only around 25.00, and a good used ridge reamer can be bought off ebay for pretty cheap. Most ridge reamers have a carbide cutting bit made to cut steel so the aluminum nozzle is very easy for it to cut. A pair of digital vernier calipers i bought off ebay for a mere 10 dollars..
    Once you have these tools, boring any nozzle to any diameter is a breeze.
    Ross
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  2. #2
    flyboy's Avatar
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    pretty cool. let us know your gains. you should be able to do this at the ramp right? .5 mm at a time.

  3. #3
    You can go .1mm at a time if you want... All it takes is a Makita cordless and yes you could do it at the ramp...

  4. #4
    Moderator RX951's Avatar
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  5. #5
    I thought 85mm was the ideal size for top end w/ the HO pump?

  6. #6
    My son (mohawk man) jeffsntx's Avatar
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    Quote Originally Posted by NateGP1300R View Post
    I thought 85mm was the ideal size for top end w/ the HO pump?
    It all depends on prop and target RPM's.

  7. #7
    Just like a race car uses differential gear ratio and tire diameter to attain desired rpms, a ski uses exit nozzle diameter and impeller pitch..

  8. #8
    Duke's Avatar
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    Good info Ross!

    Do you know what the limits are in max bore? Can the 87 be honed larger then the 85?

    I was looking at the Skat 5 degree nozzles with the interchangable rings but this might be the better way to go.

  9. #9
    Moderator RX951's Avatar
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    Quote Originally Posted by Duke View Post
    Good info Ross!

    I was looking at the Skat 5 degree nozzles with the interchangable rings but this might be the better way to go.
    I've always wanted to do that like the RXP guys do. just swap rings

  10. #10
    Moderator beerdart's Avatar
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