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  1. #1

    Cavitation issues with slx1200. Little help please..

    Hey guys I picked up a really clean 2000 SLX 1200. Went and did a compression test on it, cold engine the PSI in the holes were 121 across the board even after only about 3/4 cycles of the engine.. I was fine with that and purchased it.. It would maybe made more if I had cranked longer but thats here nore there.. Anyway the ski has a RD intake grate, not sure on the ride plate as i didn't see anything on it.. It has the aluminum wear ring/extension upgrade on it, from the looks inside the nozzle has a stock prop.. In a supper tiny chop I manged to get 59mph on gps out of it with over half a tank of gas and me ( 225 lbs) should it be faster then this?? The issue I am seeing is that once i gas this from a dig it starts to pull up on plane, then has bad cavitation to the point it will fall off from coming out of the hole. is this normal for these ?? when doing a power turn/slam turn it will fall down in the water from cavitaion.. If i bump the gas and get it rocking 2 times and gas it, it is up and gone for the most part.. I was intially thinking the previous owner shimmed the impeller to fat and that is the issue, but i have never owned a polaris ski, never thought I would lol. All in all I am impressed with this ski, it runs well.. I am looking to find what will give me the best performance, mph in calm to small chop.. I know its going to be impossible to run with the newer heavier/ longer skis in a hard chop, so I need to keep it where it is made to be really, I have been doing some reading on here, but need a fresh info as the info seems to be failry old, new things might be out or things changedsince then. Can i do the 150psi heads with a simple bolt on ? i have a extra block and heads for this also.. it is a ride in the ruff stuff, but I am into the smaller skis.. anyway what could cause this cavitation ?? What are the specs for impeller thrush shim and shim at the wear ring ? These seem to be a little different the. Other makes... Thank you all


    John


  2. #2
    hmmm. Bump one has a bit of light to shed I this ?

  3. #3
    MSX 150 guy lives on Mr. GP1800's Avatar
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    You really need to pull the jet pump and inspect everything. Your issue could be a worn or damaged impeller, the drive shaft seals may be worn. Do you get water in the hull? The ride plate may not be sealed properly. That small hull with the 1200 motor should really pull hard from a stop.

  4. #4
    You answered in the other post that it needs a .010 shim.. What are you talking about in that respect ?? I have never had one of these apart. Are you referring to the clearance between the impeller edges and wear ring tube.. This has the aftermarket stainless one in there ? The hull inside is essenitally dry. The seals were done in the past year. The ride plate is sealed up well in my opinion. I have looked over everything in that aspect of it. I have not pulled the nozzle off to do any thing else. The impeller appears to be in fine condition. No broke or bent blades. Would just having a different intake grate on it cause the issue ?? As I said it has the Rd intake grate on it..

    John

  5. #5
    MSX 150 guy lives on Mr. GP1800's Avatar
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    No shims. The space between the impeller and wear ring needs to be .010 or less.

    I suggest getting the Polaris factory manual. Everything you need to know is in there.

  6. #6
    MSX 150 guy lives on Mr. GP1800's Avatar
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    Where is your trim setting when trying to take off? With these little 2 seater hulls and a 1200 motor the trim needs to be neutral or down otherwise the nose comes up so high the pump comes unhooked.

  7. #7
    Absolutely nozel is always down on take over, sti comes in hooked with cavitation.. I am not unfamiliar with skis but with the Polaris in general I am.. I have ever had this issue with other skis so it seems like maybe it was just the nature of the ski. If it turns out the impeller is at the proper shin ( .010 or tighter ) what is the next thing to really inspect ? Ride plate or the intake grate ?

  8. #8
    MSX 150 guy lives on Mr. GP1800's Avatar
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    .020 or less is the service limit. .010 or less is ideal. You really want the jet pump to be in perfect condition. A less than perfect pump is a real performance killer.

    Air leaks anywhere into the intake area of the pump can cause what you are describing. I have a 2001 Pro 1200 and that small hull has zero slip. It just hooks up and goes.

  9. #9
    well come to find out the trim has not been all the way down as i thought it was.. If i keep the nozzle down it comes out pretty good, but still get some decent cavitation when doing hard slam turns or taking off in a chop.. But not like it was.. i guess with it being a short ski it is a little more picky then others that are longer. I am going to run it till the end of the season then go through it with a fine tooth comb and see what is going on.. I also need to go over the carbs low speed screws, has more smoke then i like at idle, is a touch lagy out of the hole from it being so rich. i just bought this so Im sure it needs to be gone over. From what i can see is all the fuel lines have been replaced with new ones, the engine is more less fresh, as I see new head gaskets and all on it.. There just isnt a lot of info on this particular ski.. i know that the way it sits and my 220lb butt on it in the calm water that a 99 xp limited, 2008 aquatrax turbo can not pull around me so that is good lol. I am happy with it overall.. I just need a few parts.. the dash read out is come and go, so need to find one of those.. other then that i have beat this thing for 2 days hard and it has been great.. I am thinking the low speed screws need to be ruffly 1 1/2 turns out correct ??

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