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  1. #1
    2000 GPRXP 4tec shooter98xpl's Avatar
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    riddle continues

    EFI ski that just turns the same rpms.
    7130 to 7150 rpms with an 85 or 87 mm nozzle. 800 or 1200 grate, still 7130 to 7150 rpms.
    The difference is that the hole shot, midrange and top end differ, but rpms stay the same. Cold or Hot.
    Anybody have any clue as to what the fuck is going on? Sometimes I'll see a spike of 7160 to 7180, but thats only when I first take off after letting it cool down. I just find it weird that with changing everything around, the ski still turns 7130 on the average. I would have thought with a 87 mm nozzle I'd gained some rpms up top, but nothing. The 800 grate, same thing, all the same rpms, speeds increase/decrease.
    Question is, I run my pettach 2500 on the 3rd plug wire with an alligator clip, even if I run it wrapped around the wire, still reads the same. Should I be on the 3rd plug wire or on the 1st or middle?
    SHOOTER


  2. #2
    I had this same type of problem on my 1200 a couple of years back. Then the #2 piston started seizing up on me. I would pull the head and get a real good look around. Put the alligator clip for the tach on the #2 plug wire on the black where it comes out of the electrical box.

  3. #3
    THE PLATE MAN JIM'S PERFORMANCE's Avatar
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    Check the phase on the crank, When my rpm's were dropping and went from a 25 pitch to a 23 pitch hardly and rpm change. My crank on 3 rd. cylinder was 8 degree's of phase.

  4. #4
    2000 GPRXP 4tec shooter98xpl's Avatar
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    Okay, I'll try the #2 plug wire. I always thought it was the #3 wire, but I'll try #2 again.
    Jim, I read your thread on that, but my ski only has 60 hours and its always been the same rpm. I've changed everything, that would suck if this crank was out of phase. I guess I will have to check that out too. I did notice that my squish was rather weird on my setup. We checked it at Leo's and it came out to .056, .055 and .051, but my compression is 152, 152, 147. The rear has a tighter squish but less compression, thinking it might be due to the volume of the dome on #3. Not sure.
    SHOOTER

  5. #5
    Robsauto2's Avatar
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    Quote Originally Posted by jims 1300 View Post
    Check the phase on the crank, When my rpm's were dropping and went from a 25 pitch to a 23 pitch hardly and rpm change. My crank on 3 rd. cylinder was 8 degree's of phase.
    +1!

  6. #6
    THE PLATE MAN JIM'S PERFORMANCE's Avatar
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    Hello Larry, If the crank is out of phase your compression will still be good.

  7. #7
    2000 GPRXP 4tec shooter98xpl's Avatar
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    Jim, do they naturally come out of phase from the factory? Reason I am asking is that Mike's ski does the same thing, no matter what, our rpms do not change what so ever. Or can the prop's diameter been cut too much that it does not have the proper clearance, maybe too much? I guess Tuesday I will take out the pump and check the wear ring clearance. I mean I gain no rpms with an 800 grate or with an 87 mm nozzle. I've chased this problem since we fixed the ski last time. But my speeds change all the time, I can go 72 mph one day and 76 mph another day. Depending on the grate.
    To check the phase would mean I'd have to pull the motor out, its still too nice to do that, hahaha.
    SHOOTER

  8. #8
    WATER WOODY's Avatar
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    .Thank Fercho for the pic.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  9. #9
    2000 GPRXP 4tec shooter98xpl's Avatar
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    tried calling you but you don't return calls, sniff sniff. You get the plate woody?
    SHOOTER

  10. #10
    THE PLATE MAN JIM'S PERFORMANCE's Avatar
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    What's odd larry is you put a 87 mm nozzle with no rpm gain and a 800 grate.

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