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  1. #1

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    Question on aftermarket impeller for more mph

    I searched a lot on this topic but didnt see anything on my machine. I have a 99 genesis with the 1165cc carb motor. Has anyone put an aftermarket impeller on the genesis and can tell if it was worth it or a waste of money. I know if you gain mph then you will lose lowend but if my machine does 55, will it do 60 with an aftermarket prop and if so, will it kill the takeoff enough to make it not worthwhile. I was just looking for more top end speed and dont want to do anything to the motor. Or would i have to change the impeller and the intake grate to make it worthwhile. It seems on my machine, 3/4 throttle will do 50 and full throttle will do 55 or is this because i have the big black "log" pipe made for lowend/pulling so my machine will never have any top end.

    Thanks for any suggestions/info


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    The Genesis is a big hull, as you know.

    The intake grate is specific to the Genesis, and as far as I know there are no aftermarket alternatives for either the ride plate or the intake grate.

    The impeller is matched to the engine power and the drag of that large hull. A different impeller might get you a little more speed, but I doubt you would see anything close to a 5mph gain from just an impeller change.

    What maximum sustained RPM are you seeing at wide open throttle? If the engine is down on power, the maximum RPM will be low, and top speed will suffer.

    Have you checked the cylinder compression?
    Check with the throttle held open, all spark plugs out

    Have you confirmed that the throttle blades are actually 100% open when the throttle level is fully squeezed?

    What you might be able to do is install a higher angle pump wedge (Item 27 in the diagram). The stock pump wedge has a four degree angle, and a six or maybe even eight degree wedge might provide some gains. Pump wedges are easy to change, and not expensive.

    What the wedge does is redirect the thrust from the jet pump slightly upwards. That forces the rear of the hull downwards at speed. That in turn lifts the bow, and reduces the overall amount of the hull that is touching the water. Less hull in the water means less drag, and more top speed.

    Other things to check are the condition of the jet pump impeller blades, the pump stator blades, and the wear ring that surrounds the impeller. Dents, gouges and dings in the blades will reduce speed. Check the clearance between the blades and the wear ring. Maximum allowed is 0.020", and a good fit will have 0.010" or less clearance.

    If the bottom of the hull is rough or gouged, that will also reduce speed.

    Excess weight in the front storage compartment will reduce speed by holding the bow down, which increases drag.

    Check the exhaust hoses for softness. If the engine has ever been overheated from lack of water cooling, that can also degrade the interior of the rubber hoses, which are normally cooled by water injection spray. If those big rubber hoses get cooked, they can delaminate internally, which affects exhaust flow, and reduces engine power. If any of the exhaust hoses feel soft, remove them and check the insides.
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  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    I don't think you will ever get 5 MPH from an impeller change. And if you did, it willl most certainly hurt bottom end performance.

    Carb adjusting would be a sure bet if it were possible for a gain like that.

    You'll most likely need to do some engine mods, and maybe try a 6* wedge to go with an aftermarket impeller to achieve what you're looking to gain.


    What kind of shape is the current impeller and stator in? If they're out of spec, that may be hurting your performance.

  4. #4
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    5 mph

    triple pipes baby yeah!!!!!!i think you'll find that when the ski gets to like 2 bars of fuel it'll pick up speed and a 6 wedge will help get the nose up more.

  5. #5

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    Thanks for the suggestions. Motor is "completely" rebuilt with about 3-4 hours on it before i winterized it. It runs excellent. Hull looks good underneath. Hoses are excellent. This is my first machine and the only other machine i drove was my uncles newer Yamaha with i think a 1300 4 stroke in it and its real fast so my Genesis would of course feel slower compared to that Yamaha. My Genesis has the updated stator installed at the rebuild, and new fuel line. Im sure the throttle goes fully open. I know these only went 55.1 mph when they were new and i am right at 55 mph exactly at 6500 rpm's

    I am sure these Genesis models with how large they are, is what they are. I know there not performance models. I havent checked the impeller but i had a guy do the stator, and i asked him recently, and he said if it was slipping when you give it gas, then you have an impeller problem, if not, then the impeller is fine. I will have to check out the impeller. I take it i just use a feeler gauge and can do it from the outside of the machine? And to look at the impeller, do i just use a flashlight and look through the back inside there with someone turning the driveshaft?

    I have not yet done a compression test after the rebuild, but will do so come spring to get some numbers to verify.

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by markdgenesis View Post
    ...I will have to check out the impeller. I take it i just use a feeler gauge and can do it from the outside of the machine?

    And to look at the impeller, do i just use a flashlight and look through the back inside there with someone turning the driveshaft?
    If you want to check the impeller with the jet pump installed, the easiest way is to remove the intake grate from under the hull (one bolt, I think), then reach in with your feeler gauges and check at several spots around the perimeter.

    The attached photos are from a Virage, but your Genesis intake and impeller will look similar. The main difference is that the Genesis intake grate and ride plate have a V shape, while all other Polaris intakes are flat where they meet the ride plate.

    The alternative is to remove the jet pump, which is not actually that hard. Remove the four LONG bolts (not nuts), the steering and reverse linkage ends, the bilge siphon hose end, and then wiggle the jet pump rearwards.

    It might be stuck in place, but it will come loose with some working back and forth. Then you can inspect the impeller directly, and also evaluate the bearings in the pump stator. The impeller should turn should turn with the stub shaft, with no play, and no grinding feel or noise.

    The Genesis wear ring is mounted to the hull, so checking wear ring to blade clearance is best done though the intake grate.
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  7. #7
    casey67's Avatar
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    Quote Originally Posted by markdgenesis View Post
    . Im sure the throttle goes fully open. I know these only went 55.1 mph when they were new and i am right at 55 mph exactly at 6500 rpm's

    , and he said if it was slipping when you give it gas, then you have an impeller problem, if not, then the impeller is fine. I will have to check out the impeller. I take it i just use a feeler gauge and can do it from the outside of the machine? And to look at the impeller, do i just use a flashlight and look through the back inside there with someone turning the driveshaft?

    I have not yet done a compression test after the rebuild, but will do so come spring to get some numbers to verify.
    The service manual claims the Genesis opperates at 6700 rpm.

    Take a look at what impeller part # is installed

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by markdgenesis View Post
    T...Motor is "completely" rebuilt with about 3-4 hours on it before i winterized it. It runs excellent.

    ...My Genesis has the updated stator installed at the rebuild

    ...I am right at 55 mph exactly at 6500 rpm's

    ...I have not yet done a compression test after the rebuild, but will do so come spring to get some numbers to verify.
    Updated electrical stator was installed?

    I thought all the 1200 engines had the Gen3 ignition, even in 1999.

    I wonder if the ignition timing is off, just slightly

    With only four hours on the rebuild, it may just need some more breaking in time.

  9. #9

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    Quote Originally Posted by casey67 View Post
    The service manual claims the Genesis opperates at 6700 rpm.

    Take a look at what impeller part # is installed
    If i remember, the rpm gauge is digital and goes up in 200rpm increments so technically it could be at 6699 rpm;s but wont show 6700 until it is at 6700 or more. I am pretty sure from what i read that is correct. I think i can check the electronic display and see what rpms was the max it has done while i was riding it.

  10. #10

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    Quote Originally Posted by K447 View Post
    Updated electrical stator was installed?

    I thought all the 1200 engines had the Gen3 ignition, even in 1999.

    I wonder if the ignition timing is off, just slightly

    With only four hours on the rebuild, it may just need some more breaking in time.
    Your probably right. You would know more than me. It was the newer part number from the 2001 Genesis or something like that, so i figured it was the updated stator. I still have the box it came in from Polaris so i could check the part number. The guy who put it in for me referred to it as the "updated version" and didnt want to order the same part number as my original although they were available from other places. Your probably right about the 4 hours since the rebuild. Had 88 hours when i bought it and if i remember 91 when the season was over. So maybe even 3 hours total.

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