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  1. #1
    TheEngineer's Avatar
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    Loss in speed after SuperCharger Rebuild

    My top end speed is down about 4 or 5 mph on my RXT. I recently did a SuperCharger rebuild through Jerry, and I also had my Pump rebuilt with new bearings and grease. So now I'm not sure which of those two things is causing the trouble.

    It is difficult to say whether or not my RPM's are lower. My RPM's have always varied based on the outdoor temperature. 8100 when it's cool outside, and about 7840 when it's really hot.

    I can say this though, during the middle of the summer, when my RPM's are maxing out at 7840, my top speed is always around 65 mph. Right now with a 7800 RPM I'm struggling to get to 60 mph. So my speed is much lower within the same RPM range. Could this have something to do with the new bearings in my pump? I noticed before I put it back on that it was much harder to spin the impellar than it was previously. Perhaps the mechanic pressurized it with too much grease?

    Thanks for any advice.


  2. #2
    TheEngineer's Avatar
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    Additional background on the problem:

    Oil level is good. Same as it was before doing the SC and Pump rebuilds.
    No visible water or hose leaks.

  3. #3
    Site Admin Green Hulk's Avatar
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    If you are still maintaining RPM then your supercharger is fine.
    Your RPM's are still too low. You want to be at 8100 RPM.

    What ski do you have and what are your mods?



    Make sure your intake grate has not pulled out at the back and is hanging down.

    Also, Make sure your wear ring is in good shape.

  4. #4
    skipSC's Avatar
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    Check your OPAS to see if they are coming up at speed.

  5. #5
    TheEngineer's Avatar
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    Quote Originally Posted by Green Hulk View Post
    If you are still maintaining RPM then your supercharger is fine.
    Your RPM's are still too low. You want to be at 8100 RPM.

    What ski do you have and what are your mods?



    Make sure your intake grate has not pulled out at the back and is hanging down.

    Also, Make sure your wear ring is in good shape.
    Yeah that's what I figured. In the past, I've usually been able to hit 8100 as long as the temperature outside is below 80 degrees. So the 7850 I'm seeing right now is definitely a little lower than expected.

    Ski is an RXT 215, completely stock. I also just had the oil seal, shaft sleeve, angled bearing, and wear ring replaced on my pump. The impeller was fairly difficult to spin by hand when I put my pump back on, so I'm thinking it might be the cause of the problem. Would too much grease make the impeller difficult to spin?

  6. #6
    TheEngineer's Avatar
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    Quote Originally Posted by skipSC View Post
    Check your OPAS to see if they are coming up at speed.
    How would I go about doing this? Just by sight while actually riding?

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    skipSC's Avatar
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    Quote Originally Posted by TheEngineer View Post
    How would I go about doing this? Just by sight while actually riding?
    I used a peice of sprinkler riser and split it. Put it on the rod and block up the paddles. Too much grease will not kill your RPM's that much.

  8. #8
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by TheEngineer View Post
    How would I go about doing this? Just by sight while actually riding?

    If your OPAS is stuck in the down position they will cause the speed loss you are seeing.

    You can install these
    http://www.4-tecperformance.com/inde...roducts_id=440

    Or just remove OPAS all together with one of the OPAS blockoff kits.

  9. #9
    TheEngineer's Avatar
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    Quote Originally Posted by Green Hulk View Post
    If your OPAS is stuck in the down position they will cause the speed loss you are seeing.

    You can install these
    http://www.4-tecperformance.com/inde...roducts_id=440

    Or just remove OPAS all together with one of the OPAS blockoff kits.
    Well I got home today and checked. Sure enough, my OPAS hose clamp had come off, so I'm going to bet that was the problem. Thanks for pointing me in the right direction.

    Jerry, I ride in ocean chop all the time so I'm very curious about this Competition O.P.A.S. kit. Do you know anyone who has used it? Does it really make a noticeable difference?

  10. #10
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by TheEngineer View Post
    Well I got home today and checked. Sure enough, my OPAS hose clamp had come off, so I'm going to bet that was the problem. Thanks for pointing me in the right direction.

    Jerry, I ride in ocean chop all the time so I'm very curious about this Competition O.P.A.S. kit. Do you know anyone who has used it? Does it really make a noticeable difference?
    Yep, you found your problem.

    Block the OPAS in the up position with that kit or some PVC pipe and you will never have to worry about this problem again.

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