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  1. #1

    65U tuning help!!!

    I took the 97 out on Friday after I got done with her. I just put on a fresh top end with Dan Lamey ported cylinders. While I was tuning I reached down to adjust the carbs and I noticed the intake was ICE cold after 15min of run time?!?! I have never noticed this before. I think I'm way off on my jetting but I dont think this is my problem. Does that sound normal?? I think I'm also getting a lot of prop spin out of the hole. I will pull the pump tomorrow and see what I have in it, maybe you guys could help with that too. Thanks

    Riva Head 41cc domes
    Dan Lamey ported cylinders
    Riva/Buckshot Mod carbs 115 main 130 pilot 2.3 N/S 115 spring
    Riva CDI
    V force reeds


  2. #2
    bainer1290's Avatar
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    How was it running? What rpm were you getting to?

  3. #3
    DAGO RACING CREW 97GPSLEEPER's Avatar
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    The intake is never going to be hot, especially at the top of the intake. It may get a little warm where it ties into the crankcase due to heat transfer.

    What size prop are you running? You may be underpropped and spinning it. Is your intake grate sealed?

  4. #4
    I didnt really hammer on it yet since its not really broke in yet. The tiny tac that I had on it was broken. I have another one I will be putting on and hopefully heading to the lake tonight. I just pulled the prop out of it and its a Solas YD-SC-I 13/19. What do you guys think about that. I read everywhere that the J prop is the way to go. It just seems to spin like crazy out of the hole. (the I prop)

    Another thing. I was testing the compression and it seems to be low. I have the riva head with 41cc domes. Book says I should be running like 155 psi. I'm at 125 in all three. Would the porting of the cylinder change the compression numbers by that much?

  5. #5
    I knew it didnt get really hot but this thing was ICE cold. I just thought it seemed weird. The intake is sealed and I'm running the R&D aquavein intake grate. Prop is posted above YD-SC-I 13/19 I have a Skat prop too but its unmarked or the marking is inside the hub and I dont have a tool to get it off the shaft.

  6. #6
    DAGO RACING CREW 97GPSLEEPER's Avatar
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    I don't know anything about Lamey porting, but I hear it is good and somewhat aggressive. I can't imagine the porting bringing down the compression to 125psi. Having said that, make sure the gauge is somewhat new and a Snap-on or another high end gauge. I have seen a difference in gauges by 10 psi. And make sure the throttle is wide open and the battery is fully charged.

    The J prop I have is actually a 13/19 (Group K repitch). I do not spin out of the hole. I pay close attention to sealing the intake grate and intake duct. You may just have an animal on your hands and need a steeper prop.

  7. #7
    bainer1290's Avatar
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    What's your elevation? Keep in mind that for every 1000' above sea level your compression drops 5-7 psi. Majority of the specs for domes are given for compression at sea level.

  8. #8
    I believe I 'm only about 400-600 above sea level.

  9. #9
    bainer1290's Avatar
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    Quote Originally Posted by HCP Designs View Post
    I believe I 'm only about 400-600 above sea level.
    That shouldn't make too much of a difference then. I know that porting can change the compression depending on how drastic it is. You may want to check with the person that ported them to see.

    On the other hand the prop could be the issue also. I think you need to continue the break in and get that tach hooked up to see what the rpms look like on the top end once you have it sialed in. That will make it easier to see if you need a steeper prop.

  10. #10
    cheatin' piston popper addicted's Avatar
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    My ported motor runs 37cc domes for 150 psi at nearly sea level. Any time the exhaust port is raised, your compression will drop.

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