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  1. #1

    Ultra 250x not hitting full rpms

    Hi, I have a 250x that I just rebuilt the motor I'm with all new oem parts. (About 2k worth.) Now, the ski runs amazing and pulls really great. But after I broke the engine in, I took it out for a full throttle pass and only hit about 50 -55 mph. The rpms only reach about 6400 to 6500. Feels like it's hitting a rev limiter. What should I look for? Boost leak?


  2. #2
    Fat Man, Little Boat Region8Ultra250X's Avatar
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    Check all the exhaust hose clamps, boost clamps, belt tension.

  3. #3
    Quote Originally Posted by Region8Ultra250X View Post
    Check all the exhaust hose clamps, boost clamps, belt tension.
    I checked all clamps, and the belt is tensioner right in the middle of the tensioner gauge. I took the seat off and ran it and got maybe 100 more rpms so I don't think I have an exhaust leak, plus all the gaskets are new. When I had the seat off it kinda sounded like it was hitting a rev limiter At full throttle. . Spark plug wires maybe??

  4. #4
    Quote Originally Posted by MWHC View Post
    When you were breaking it in did you ever make any WOT passes? Did it run better then? What I'm getting at is this something that you've noticed develop or was it this way from the start after you rebuilt it?
    From the start after the rebuild. It hasn't gotten any worse. If anything maybe a little better. But still missing about 1000 rpms

  5. #5
    Quote Originally Posted by MWHC View Post
    Run through all the basics, fuel, spark, and verify timing first to eliminate all the easy stuff.

    I missed timing on an engine by a tooth one time and it wasn't extremely noticeable untill upper rpm then just quit making power.... basic stuff first though!
    Wouldn't it be quite noticeable if timing was off even 1 tooth? Because it runs great.

  6. #6
    Ok. I did the timing advance mod, and got 7100 rpm and 63mph on the GPS. But I'm still missing rpms. It feels like it's breaking up at 7100rpm. I will clean out the intercooler next. Boost is at 9.5 at 7100rpm

  7. #7
    Let me out of here......I need to go on Greenhulk!
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    Quote Originally Posted by cklemm View Post
    Ok. I did the timing advance mod, and got 7100 rpm and 63mph on the GPS. But I'm still missing rpms. It feels like it's breaking up at 7100rpm. I will clean out the intercooler next. Boost is at 9.5 at 7100rpm
    Thinking he meant the cam timing. Make sure the marks line up

  8. #8
    Quote Originally Posted by TMiller View Post
    Thinking he meant the cam timing. Make sure the marks line up
    No, I know he meant cam timing. If i was off by 1 tooth wouldn't that be quite noticeable? I mean, it starts and runs great. I did the timing advance mod just to do it.

  9. #9
    Quote Originally Posted by cklemm View Post
    No, I know he meant cam timing. If i was off by 1 tooth wouldn't that be quite noticeable? I mean, it starts and runs great. I did the timing advance mod just to do it.
    Ok, so I cleaned the intercooler and found a SMALL amount of water in the bottom of the intercooler. Rigged the intercooler up to a hose to test for leaks and didn't see any leaks inside it. Put everything back together and it revved to 8700 rpm out of water but when I put it in the water will be the real test. The bov is not leaking. How does the pressure relief valve work? Shud it be blowing air at idle? Thanks

  10. #10
    11FALLINE's Avatar
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    A small amount of water in the cooler is normal as it condenses moisture out of the charged air. DON'T make a habit of revving it that high out of the water. It is a pointless test and can only do harm to your motor with no load. The relief valve does blow air at idle when the motor is sucking vacuum thru the small hose. Under throttle there is pressure in the small hose which block the relief valve to provide boost. If you push on the inside of the valve and it feels pretty stiff its probably okay.

    You need to check off the other items people have mentioned. Fuel pressure test on the water is ideal but the 3 second fuel prime would give you an idea on whether you're getting enough fuel.

    Using the search button will get you answers a lot faster than waiting for response. There are probably hundreds of threads with people trying to get these machines back to full potential.

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