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  1. #1

    Please Help with 1999 Polaris Genesis carbureted ski.

    Hello, I just picked up my first ski it"s a 1999 Polaris Genesis carbs it has 120 original hours. Today I took it out and the fastest it would go is 40mph at 4500 rpm thats it. Calm water I am 216lbs and it had 1/4 tank of fuel. I checked the plugs all seem okay, Throttle opens all the way up. I have been reading on all the information but just wanted some input maybe that is all it will do. When I put my family on the ski same thing 40mph at 4500 rpm no changes. I checked the hoses I can squezze them on the exhaust didnt notice anything to irrigular but never had one. I also started replacing the gas lines and didnt notice anything apnormal no gel or anything. Carbs seem really clean and taken care of. Any information would be great other than me taking it to a shop. I read about reeds so much information just dont wanna do the wrong thing it runs and I hate to do something to make it worse. Thank you again for any information...


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome

    Check cylinder compression.

    What is the maximum sustained RPM while riding at full throttle?

    Exhaust hoses should be VERY firm when squeezed. No softness or bulged areas.

    When the engine is running in the water, are all three cylinders about the same temperature? You should be able to put your hand on the cylinders for several seconds without burning yourself.

    If one cylinder feels cooler than the others, that means it is not producing power.

  3. #3
    The maxium rpm at full throttle is 4500 rpm and on spedo varied from 38.6 to 40mph. The hoses are a little soft I can squeeze them sort of like a radiator hose there not rock hard. I know the ski is a very big ski and maybe it"s only good for 40mph I just wanted to make sure also the 4500 rpm seems a little low to me. I checked the plugs they look pretty good. I also checked to make sure when you pull throttle it opens all the way and it does. If that is top speed that is okay I just want to make sure. Also when you punch the throttle it doesnt seem to take off super fast as one would imagine a two stroke but then again im new so I dont know. Any information would be great or what you think it should be doing. Thank You..

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    Click avatar for tech links/info, donation request K447's Avatar
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    Check cylinder compression.
    All spark plugs out, throttle held wide open.

    Max RPM should be about 6500, and it should pull quite strongly from launch. Top speed will be over 50mph when running properly.

    You are way down on power. Just need to figure out why.

    Click the link below

    Polaris Domestic (red) engine

  5. #5
    Thank you I apericate it but the motor thing might be a little more than I can handle. I will check it out the best I can though. What about a carb issue would that be more previlant than the engine and compression. I did read through all the articles. Other than compression issues what are most common I mean 4500 rpm to 6500 rpm is a huge jump or loss.

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    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by K-9 View Post
    ...Other than compression issues what are most common I mean 4500 rpm to 6500 rpm is a huge jump or loss.
    Low compression in one or more cylinders would be the number one reason for lack of power/RPM.

    Carburetor/fuel and ignition problems are always possible, but checking compression is easy to do, and provides solid info regarding the internal health of the engine.

    A basic compression gauge kit is inexpensive (maybe $20). Any friend or neighbor who repairs engines will have one (or several).

    Unlike a land vehicle, a PWC engine always has the water load on the jet pump impeller. If the engine torque and power are low because one cylinder is weak, it just cannot twist the impeller hard enough to get fully into the power RPM band for the 'good' cylinders. Hence the really low RPM in the water.

  7. #7
    Okay I will go to advance in the am and pick one up. What should I be looking for on pressure on the cylinders. I just watched the video on checking engines on your links and they found a carb not running right.Maybe I will luck out. But I will pu gauge in the am screw it in and check each cylinder is there an allowable variace for each one or should they all be the same. And if there is a problem with low compression I guess I am out of luck I am sure its reall expensive. What all new engine.

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    Quote Originally Posted by K-9 View Post
    ...What should I be looking for on pressure on the cylinders?

    But I will pu gauge in the am, screw it in and check each cylinder

    ...is there an allowable variance for each one or should they all be the same?

    And if there is a problem with low compression I guess I am out of luck I am sure its really expensive...
    Compression gauges vary somewhat in absolute pressure readings, but typical compression numbers would be about 120PSI, give or take.

    A healthy engine will have each cylinder PSI within 5% of the others. More than a 10% PSI difference from highest to lowest cylinder means the engine has a problem.

    Depending on what you find, we can discuss your options.

  9. #9
    Okay good news, I got a compression gauge checked all three cylinders all at 130 on the gauge. I first checked by cranking three times with lanyard off got 130psi, then I put lanyard in unit fired all cylinders firing with plug out. I did change plugs while I had them out gaped them per mfg specs at .028 they are ngk plugs br8es. Should I take off the carbs and check the individual filters on each carb? I just dont wanna get into ripping the carbs all apart as I have never done that and I dont have any parts or o-rings or gaskets. Unless I really need to do it. Can I remove the carbs and check the filters on each one without getting to into them. Any other ideas. Thank You again...

  10. #10
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    You have good compression on all three cylinders

    You have strong spark on all three cylinders? Good.

    That leaves the fuel system, from fuel tank through the carbs.

    I would say now is the time to purchase three carb rebuild kits. Genuine OEM kits, not aftermarket.

    There is plenty of info around here to guide you in the rebuild. Work on one carb at a time. Keep track of which cylinder each carb came from.

    Take your time, and work in a clean workspace. Cleanliness and care are the keys to successful carburetor work.

    Take photos as you go, in case you need to review where something was before you took it off.

    Be sure to spray carb cleaner through the small orifices and passages in the carbs. Wear eye protection when spraying the cleaner.

    Once everything is clean and dry, work through the re-assembly.

    Once you have done a couple, you will find the work goes faster.

    Before you install the rebuilt carbs, replace all the fuel lines.

    Also clean out and inspect the fuel selector valve. Replace and lightly grease the O-ring if there is any question about how well it is sealing.

    It is important that the fuel system be completely free of air leaks, as the fuel lines are under suction from the fuel tank up to the fuel pump on the carbs.

    Air leaks allow bubbles into the fuel flow, which weakens the fuel pressure into the carbs.

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