terrible holeshot!!
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terrible holeshot!!

  1. #1
    Senior Member rogerroost's Avatar
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    Default terrible holeshot!!

    what causes lots of cavation on hard start?? 460 rogers, don't know any thing about the jet,other than it's a berk jg (i think), place divertor,loader.
    is this a sign the wear ring is done?

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    Senior Member jetboatperformance's Avatar
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    Likely that Inspection of the WR and Impeller will tell the story , but also look for "air leaks (packings , cleanout oring ) Tom

    heres some good info from AT: "understanding your jet boat"
    Higher than normal RPM's, lack of thrust, slipping clutch feel, engine racing and no go?

    1. Blockage: The most common problem is weeds and stones blocking the intake grate. Also be aware of ski rope, fishing line and plastic bags winding around the pump shaft. Small sticks and stones can become lodged in the impeller affecting the performance dramatically, objects trapped in the impeller can cause the rotating assembly to be out of balance, causing severe vibration. Make sure the water passage through the jet is clear.

    2. Impeller wear: The heart of the jet is the impeller, and its condition. If you run in shallow gravel beds or across sand bars the leading edges will become dull and inefficient. Pumping sand will increase the wear-ring to impeller clearance. Causing cavitation and loss of performance.

    3. Bowl / stator vanes: Its not too much of a problem, but the leading edge of the fixed stator vanes can become blunt and damaged.

    4. Air leaks: If excessive air leaks into the intake ahead of the impeller, the jet unit will "slip". Possible sources of air leaks are though a faulty gland seal, which is usually accompanied by a static water leak into the boat when standing idle.

    So if the gland is worn out and leaking into the boat with the engine off, it can also suck air when accelerating on to plane, and if this happens, then the thrust is reduced dramatically. Air can also be introduced into the system via the inspection cover, so you will want to make sure the cover is tight

  4. #3
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    Quote Originally Posted by jetboatperformance View Post
    Likely that Inspection of the WR and Impeller will tell the story , but also look for "air leaks (packings , cleanout oring ) Tom

    heres some good info from AT: "understanding your jet boat"
    Higher than normal RPM's, lack of thrust, slipping clutch feel, engine racing and no go?

    1. Blockage: The most common problem is weeds and stones blocking the intake grate. Also be aware of ski rope, fishing line and plastic bags winding around the pump shaft. Small sticks and stones can become lodged in the impeller affecting the performance dramatically, objects trapped in the impeller can cause the rotating assembly to be out of balance, causing severe vibration. Make sure the water passage through the jet is clear.

    2. Impeller wear: The heart of the jet is the impeller, and its condition. If you run in shallow gravel beds or across sand bars the leading edges will become dull and inefficient. Pumping sand will increase the wear-ring to impeller clearance. Causing cavitation and loss of performance.

    3. Bowl / stator vanes: Its not too much of a problem, but the leading edge of the fixed stator vanes can become blunt and damaged.

    4. Air leaks: If excessive air leaks into the intake ahead of the impeller, the jet unit will "slip". Possible sources of air leaks are though a faulty gland seal, which is usually accompanied by a static water leak into the boat when standing idle.

    So if the gland is worn out and leaking into the boat with the engine off, it can also suck air when accelerating on to plane, and if this happens, then the thrust is reduced dramatically. Air can also be introduced into the system via the inspection cover, so you will want to make sure the cover is tight
    this is some good info here think i may have an air leak issue im finally gettin it wet hopefully tonight what is the at thing you refer too understanding your jet thanks
    domenic

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  6. #4
    Senior Member OkieDave's Avatar
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    or it could be too much weight in the boat...I'd suggest you let that chic in your Avatar ride with me!

  7. #5
    Senior Member jetboatperformance's Avatar
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    Quote Originally Posted by bgblock View Post
    this is some good info here think i may have an air leak issue im finally gettin it wet hopefully tonight what is the at thing you refer too understanding your jet thanks
    domenic
    Domenic AT = American Turbine to info is from their web site under Tech help

    Quote Originally Posted by OkieDave View Post
    or it could be too much weight in the boat...I'd suggest you let that chic in your Avatar ride with me!
    Boats are very weight sensitve ya know ..

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    Senior Member Widetrack's Avatar
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    Packing glands seem to be the most common! But as said there can be other problems! As of late I have seen packing pulled that would be burnt up! FWIW! WT


    SOMEONE SAID YOU CAN'T TAKE IT WITH YOU! SO,IM BURNING IT UP ONE GALLON AT A TIME!
    WT

    WFL Crew!!!

  9. #7
    Senior Member jet460's Avatar
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    When I got my boat, (460/12JC) the teflon ring on the nozzle, and the packing were toast, and the bowl gasket leaked badly. I got 5000rpm's and not much else.
    Fixed those 3 things and now I have 4500rpm's and a MUCH better launch.
    Spraying water up, down, and sideways just throws power away.

  10. #8
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    Quote Originally Posted by jetboatperformance View Post
    Domenic AT = American Turbine to info is from their web site under Tech help



    Boats are very weight sensitve ya know ..
    thanks domenic

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