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  1. #1
    RXP 260 X Short Course Veteran RXP244's Avatar
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    Pump Nozzle sizes

    Anybody prepared to divulge the size of the nozzle they are running in their conversions. Yammy pump or Seadoo. I am looking at reducing the size of mine dramatically. Currently at 80mm but want to go way smaller. Top speed only, holeshot not important.

    Thanks Mark.


  2. #2
    Autosport's Avatar
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    Depends on the prop I'm running and the weather/temprature. I use a nozzle with an interchangeable ring, in winter I need to go down in nozzle size, in summer it comes back up, I normally don't run any smaller than an 81mm, and if I still need to bring Revs down, I step up to a taller pitch prop.

    I normally run between 81 and 83mm nozzles and have run 85mm in the past.

    I run similar to this, just make your own rings if you want smaller, but with the pressure at the speeds you're running, I don't know if it is a good idea unless you've got that Ring in there nice and secure.
    http://www.ebay.com.au/itm/330757494...84.m1558.l2649

  3. #3
    ksalles's Avatar
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    I've only used the Yam stock 155 setup on my conversion. The ski has been its fastest with the 83mm (but very close with the 85.5mm), and I've noticed with my setup at least, using different nozzles doesn't drastically change rpm as it does in other applications. One of the last times I went out, I changed from the 85.5 to the 87 and only saw 10 rpm increase. Thats not a typo, 10 rpm. I put the 85.5 back on and lost the 10 rpm. Same day, same water, all withing thrity minutes basically. I've run the 87, 85.5, and the 83mm nozzles. I like the 85.5 for all around and the stock sho steering nozzle. I run the a stock SHO steering nozzle bored to 92mm when I run the 87mm nozzle...basically for piece of mind. I have run the 87mm with the stock SHO steering nozzle though with no problems. It's all what your setup likes. Alot of input and helpful information on this site, but not everyone's equipment responds the same to changes...regarless what it is. Sometimes the same applies, but often different individuals will get different results with similar setups.

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  5. #4
    RXP 260 X Short Course Veteran RXP244's Avatar
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    Thanks guys,

    But is there nobody that has gone smaller than 80mm. I am thinking that even if the rpm does not drop that much, surely the velocity of the water exiting the pump will increase and result in a speed increase. Or am I on drugs?

  6. #5
    Having Fun jp1300r's Avatar
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    What kind of rpms are you trying to stay down to? I am sure there is a good reason why nobody has tried to nozzle down below 80mm. Fear of a big stuff at 95mph+, maybe. I would just turn more r's myself. The SD engine can take. IMO From what I know you need to be willing to turn up to 10K to get to 100 mph.

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  8. #6
    jetskibum1's Avatar
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    I ran 71mm and blew the presure nozzle clear off leaving the 4 bolts in place with bits of casting still around them, the steering cable tore out taking the electrical box with it and then filled with water.
    The revs came down though and the speed went up! Now just to find the happy medium Start small, work up and use a good AM nozzle.
    Bet there are pics of my disaster somewhere which I can put up.

  9. #7
    Duke's Avatar
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    Anything below 83 is asking for trouble IMO. Just adjust the prop to that. The tunnel pressure goes through the roof when going that small.

    Also if your running huge power and speed with the SD pump, just machine the Yami nozzles to fit. No way can the SD nozzles take that kind of pressure and you will get hurt.

    My .02

  10. #8
    RXP 260 X Short Course Veteran RXP244's Avatar
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    Quote Originally Posted by Duke View Post
    Anything below 83 is asking for trouble IMO. Just adjust the prop to that. The tunnel pressure goes through the roof when going that small.

    Also if your running huge power and speed with the SD pump, just machine the Yami nozzles to fit. No way can the SD nozzles take that kind of pressure and you will get hurt.

    My .02
    Thanks Duke

    I think I'll stay with the 80mm nozzzle at the mo. It's holding in there. But I'll have a look at my Yammy nozzle and see whats involved. Also, I don't think I've got anymore in the prop I've got. 15/22R bent heaps!. It's so close to the stator vanes now. I'm going to have to find some speed in the hull and probably turn more R's than I first thought. I still haven't run the boost past 15 psi yet. Early days.

  11. #9
    Autosport's Avatar
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    What about a larger pump? Sounds like you sure do have the power to run one?

  12. #10
    RXP 260 X Short Course Veteran RXP244's Avatar
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    Quote Originally Posted by Autosport View Post
    What about a larger pump? Sounds like you sure do have the power to run one?
    Steady on!

    I haven't even turned this pump to max r's yet. Pretty sure we Reflashed this ECU a year or so ago to about 9100 to 9200, limter at 9300? We just can't remember, so I've still got to do that. And I'll do that with just a bit more boost. And see where we're at and then go from there.

    I'll get there, just haven't had a chance to get back to the water after the couple of small issue's with the tank and all.

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