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  1. #1

    wtb r&d intake 99 gp12

    I tried to post in classified ,but it would not let me. So if this could be moved or admin help me out. Title say it all i'm looking for r&d intake gate. please send pics of what you got and price to sell prefer local sale. Or if some has a better idea on how to eliminate cavation.


  2. #2
    pilo704's Avatar
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    trim tabs help a hole lot depending on what year ski you have..

  3. #3
    Old Ski Insanity w/rpm500's Avatar
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    Quote Originally Posted by gp1200 View Post
    I tried to post in classified ,but it would not let me. So if this could be moved or admin help me out. Title say it all i'm looking for r&d intake gate. please send pics of what you got and price to sell prefer local sale. Or if some has a better idea on how to eliminate cavation.
    that grate would be a nice addition to your ski ,but this all depends on when your cavitating... out of the hole or at speed...

    out of the hole, a grate change pretty much wont help you (over a stock unit). that cavitation is affected by your impellar and the condition of your pump ...

    but, the grate will affect cavitation at speed if its not allowing enough water into the impeller to keep it loaded...

    an impellar thats wore out at the blades outer edge will cavitate(slip) along with one that is not smooth and shaped properly at the leading edge.(turbulance)

    a wear ring thats 'worn' will let water pressure bypass, which causes the impellar to slip again .

    a hub vein thats been damaged will affect cavitation as it wont let the water out smoothly...its damage impeades flow and would then cause the impellar to beat the water(cavitate) and not accelerate it thru..

    if the condition of your lower end is good you can have the impeller repitched to higher blade angles..a shop would need info (rpms) at hole shot and at top speed in determining what you need done along with what your looking for... quickness or top mph.....hope this helps!!

  4. #4
    Old Ski Insanity w/rpm500's Avatar
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    Quote Originally Posted by pilo704 View Post
    trim tabs help a hole lot depending on what year ski you have..
    ....in keeping the pump's intake in the water at speed,yes these would help.. but not during hole shot's cavitation.. we dont know yet when this is happening to him

  5. #5
    Quote Originally Posted by w/rpm500 View Post
    that grate would be a nice addition to your ski ,but this all depends on when your cavitating... out of the hole or at speed...

    out of the hole, a grate change pretty much wont help you (over a stock unit). that cavitation is affected by your impellar and the condition of your pump ...

    but, the grate will affect cavitation at speed if its not allowing enough water into the impeller to keep it loaded...

    an impellar thats wore out at the blades outer edge will cavitate(slip) along with one that is not smooth and shaped properly at the leading edge.(turbulance)

    a wear ring thats 'worn' will let water pressure bypass, which causes the impellar to slip again .

    a hub vein thats been damaged will affect cavitation as it wont let the water out smoothly...its damage impeades flow and would then cause the impellar to beat the water(cavitate) and not accelerate it thru..

    if the condition of your lower end is good you can have the impeller repitched to higher blade angles..a shop would need info (rpms) at hole shot and at top speed in determining what you need done along with what your looking for... quickness or top mph.....hope this helps!!
    Thanks for the lesson W
    Here's what I got I took a stock 97 gp 12 an swapped everything to a mint 99 gp8 pv hull. Very easy swap.Only issues is the speedo does not work after 5mph. And for some reason it seams alot faster reason being is there are skis I raced last year and now I can beat them. I never had a cavataion prob with the 97. I did not put tabs on it. Becasue I'm useing the 97 ride plate. If leave the trim in netrual it not to bad but if i trim up it's real bad. When i take my 8 yr olr for a ride it does cavatate on take off.I did shim the plate with 3 SS washers in the holes closest to the intake. that seam to help. I hope that's right i get confused when you guys say front - back holes? I usally ride 1 -2 ft of chop. Lake Huron.I've owned the gp 12 for 8 yrs and never had a impeller issue.With it running faster I'd think the the w/ring and impeller are good. gp12 hull was just shot bottom and took a hit in the front (dock).

  6. #6
    Old Ski Insanity w/rpm500's Avatar
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    Quote Originally Posted by gp1200 View Post
    Thanks for the lesson W your welcome . its how we learn in oldschool... its a pass down
    Here's what I got I took a stock 97 gp 12 an swapped everything to a mint 99 gp8 pv hull. Very easy swap.Only issues is the speedo does not work after 5mph.try a wheel height adjustment , shimming of plates will mask its water flow and sensativity some what.. And for some reason it seams alot faster reason being is there are skis I raced last year and now I can beat them.99 is a better hull ..bottom was changed..,as now with shim's in front it sets higher and is faster over the water (less hull in the water to slow you down) ... I never had a cavataion prob with the 97. I did not put tabs on it. Becasue I'm useing the 97 ride plate. OK, i take it this is the 1200 in the 800 hull and that you are following scotts recomendation on plate adjustment by washering the front bolts .. this changes the angle the ski rides at speed... think now that the whole ski is riding at this angle.. your intake now sets higher in the water flow.. true the ski is faster but, you will also heve more issues in anything other than glass in reguards to pulling more airated water into your pump... by shimming the back bolts you are driving the hull into the water ,(slowing you down somewhat) but as you are now picking up solid dense clean water, so you will get less cavitation If leave the trim in netrual it not to bad but if i trim up it's real bad. once again the angle is affected ...up trim lifts the ski higher in front 'cause its trying to push down in back(think of applying 1oo lbs more force onto the back.. where would the ski set with that pressure ? up in front, down in back.. till the plate angle overrides its force with force... When i take my 8 yr olr for a ride it does cavatate on take off.even more rear down force..and also more load on the impellar to push water..this is why xlt's have different impeller pitches and nozzel angles..I did shim the plate with 3 SS washers in the holes closest to the intake. that seam to help. I hope that's right i get confused when you guys say front - back holes? I usally ride 1 -2 ft of chop. Lake Huron.ME, IN THOSE CONDITION..would force that nose in,(shims in rear)I'd want sure handleing..ok ,yes, with the nose out/shimmed front you will skim those waves tops more effectively,but in a much looser ride... i dont think your going hunting for speed demon's here....I've owned the gp 12 for 8 yrs and never had a impeller issue.With it running faster I'd think the the w/ring and impeller are good. gp12 hull was just shot bottom and took a hit in the front (dock).your prob right,but do a visual on it anyway with a flashlight.. check your gap (spec. .006 to .024) and leading edge with a mirror( a clean line wih a slightly rounded front more like a butter knife edge, not sharp like a steak knife)

    PLEASE try shimming in the back and not the front.. you may like the results better than shims in the front, for your riding style and riding conditions ...

  7. #7

    shims

    W do you think I should try more the 3 washers?

  8. #8
    pilo704's Avatar
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    1/2 inch right eric?

  9. #9
    Old Ski Insanity w/rpm500's Avatar
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    Quote Originally Posted by pilo704 View Post
    1/2 inch right eric?
    MY gp760 has a .46 inch stack(not quite the 1/2 inch) on the rear with NO washers on the front... your 1200 would be a bit heavyer AND faster so experiment with different thicknesses in there...

    Note: go thru the washers at the hardwear and try to get em all the same thickness as most are stamped out of variing thicknesses of 'scrap' cutoffs ...

    Also... you may have to drop the front with a washer and possibly have to add another again ,at the rear when your close to your ideal ride angle...this is to line up the plates leading edge smoothly with the grate...ideally you want smooth transition with the grate's trailing edge, at the gap where they butt up...

  10. #10

    Thumbs up better results

    Quote Originally Posted by w/rpm500 View Post
    PLEASE try shimming in the back and not the front.. you may like the results better than shims in the front, for your riding style and riding conditions ...

    I switch the shims bout 3/8 to the rear none in front conditions were calmer.I did notice it seemed to stay in the water alot more almost like it was being pulled down more. ran best trim in "N" 55.3 GPS, I still think has more in it ,feels alot faster.next weekend I'm gonna take washers out and try again Now that I got the GPS on it.I'm kinda leaning on not doing a grate. You recommend if i do a grate stuffer or top loader compression should be 155 correct? and a prop change ,what about a stock grate modded 2 bars out whats your thuoght on that, keep in mind our season are short up here and with kids and all my toys come second and i ride only on weekends. If i could get closer to 60 I'd be content, not many up there are faster.

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