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  1. #1
    abarrassr07's Avatar
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    98 xpl cavitates unless trimmed up

    my xpl cavitates unless it is trimmed all the way up, during turns if i slow down too much it will catch air and not suck in water. i put the r n d ride plate on it and its a little better, i can take off trimmed all the way down or all the way up and turn sharp trimmed down and go, but when i trim anything in the middle its still catching air. any thoughts to what it might be, stock impeller,


  2. #2
    JayZ's Avatar
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    i had similar issues when i re-installed my ride plate. turns out i had to put some 'right stuff' where the intake grate meets up with the ride plate. i had gone and resealed everything except that spot and had cavitation. go figure it was the last spot that needed the sealant.

  3. #3
    abarrassr07's Avatar
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    well i sealed off the r n d ride plate the other day with marine silicone, ill check it out this after noon, but would that cause it to not cavitate trimmed all the way up and all the way down, just any where in the middle it cavitates. could the wear ring cause it to do that?

  4. #4
    JayZ's Avatar
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    mine did the same thing. trimmed all the way up, no cavitation. turn hard left or right when taking off, no cavitation.

    if your wear ring was no good, it would cavitate all the time.

  5. #5
    abarrassr07's Avatar
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    Quote Originally Posted by JayZ View Post
    mine did the same thing. trimmed all the way up, no cavitation. turn hard left or right when taking off, no cavitation.

    if your wear ring was no good, it would cavitate all the time.
    i got ya.......thanks for the help

  6. #6
    SURFnTURF's Avatar
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    Sounds like the pump seal has gone bad or the pump shoe isnt sealed properly. Seems like when you trim it in a certain position it temporarily seals the leak. I would start at the liner if thats ok reseal the pump to the shoe if still is a problem reseal the shoe.

  7. #7
    abarrassr07's Avatar
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    Quote Originally Posted by SURFnTURF View Post
    Sounds like the pump seal has gone bad or the pump shoe isnt sealed properly. Seems like when you trim it in a certain position it temporarily seals the leak. I would start at the liner if thats ok reseal the pump to the shoe if still is a problem reseal the shoe.

    ok. i pulled the pump out. unbolted it and it came right off, had no sealent around it what so ever, I dont know if the pump shoe should be sealed on the sides but it was not, so i ran a bead down both sides. I bought that neoprene stuff from walmart, can that be used for a seal for the pump. Is that the problem with the cavitation?

  8. #8
    SURFnTURF's Avatar
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    Quote Originally Posted by abarrassr07 View Post
    ok. i pulled the pump out. unbolted it and it came right off, had no sealent around it what so ever, I dont know if the pump shoe should be sealed on the sides but it was not, so i ran a bead down both sides. I bought that neoprene stuff from walmart, can that be used for a seal for the pump. Is that the problem with the cavitation?
    Yep thats your problem , The pump shoe (big black plastic moulded piece that the pump bolts up against) should be removed and resealed back against the hull using sikaflex sealant. Then the pump should be sealed to the shoe or if a later year 99 up they have a rubber seal that can be re used.
    I doubt if you will fix the problem by just sealing the perimeter of the shoe as this has alot of load placed on it by the jet pump . It might work but the best way is to remove the shoe entirely and reseal it.Its a pain as it has 4 nuts on the inside of the hull that have to be removed so as to get it out. Then it has to be shimmed the same way it was put in at the factory.Takes a couple of hours from start to finish but once done right cavitation is gone.
    My stock prop has been welded on the perimeter edges by les cooke here in Australia and then machined back so as to give zero clearance between the liner and the prop , back in 99 les did this on all his stock race boats and this gives absolutely no cavitation from the prop.
    Another little mod he does is bore the cylinders of the engine 3 degrees away from the exhaust side so the piston is now creating more power to the side of the crank instead of the top this gives more torque which is what 951s need.

  9. #9
    abarrassr07's Avatar
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    Quote Originally Posted by SURFnTURF View Post
    Yep thats your problem , The pump shoe (big black plastic moulded piece that the pump bolts up against) should be removed and resealed back against the hull using sikaflex sealant. Then the pump should be sealed to the shoe or if a later year 99 up they have a rubber seal that can be re used.
    I doubt if you will fix the problem by just sealing the perimeter of the shoe as this has alot of load placed on it by the jet pump . It might work but the best way is to remove the shoe entirely and reseal it.Its a pain as it has 4 nuts on the inside of the hull that have to be removed so as to get it out. Then it has to be shimmed the same way it was put in at the factory.Takes a couple of hours from start to finish but once done right cavitation is gone.
    My stock prop has been welded on the perimeter edges by les cooke here in Australia and then machined back so as to give zero clearance between the liner and the prop , back in 99 les did this on all his stock race boats and this gives absolutely no cavitation from the prop.
    Another little mod he does is bore the cylinders of the engine 3 degrees away from the exhaust side so the piston is now creating more power to the side of the crank instead of the top this gives more torque which is what 951s need.
    something to think about, well thanks for the info, ill let you know how it does as soon as i finish getting all the parts in, just ordered a billet head with the 50cc domes and a 15-20 solas concord so ill keep you updated. thanks again

  10. #10
    SURFnTURF's Avatar
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    Quote Originally Posted by abarrassr07 View Post
    something to think about, well thanks for the info, ill let you know how it does as soon as i finish getting all the parts in, just ordered a billet head with the 50cc domes and a 15-20 solas concord so ill keep you updated. thanks again
    Ok , some times the 15/20 is too tall for the xpl and will knock the revs down a little. I have seen them with 3 different pitches on the trailing edges of the blades on the same prop. I like them at 14/19 personally as I am a surf rider. Remember to check your squish before you start to open her up.

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