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  1. #1

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    Thumbs up SKI PERFORMANCE and HOT WEATHER

    Just a reminder to everyone! Now that the hot dog days of summer are upon us with temps in the 90-100 range and humidity in the 70-95% range and water temps reaching 90*+ your ski can be off as much as 100-125 rpm's and top speeds off as much as 2-4 mph depending on how bad the weather realy is. When the weather gets this bad and most motors tend to run even richer due to the lack of good cool, dry air. The only thing you can do is try a little less pitch on a prop and if you are a good tuner you can adjust your carbs/efi fuel mixture to correct for this time of year ( don't forget to re- tune when the fall gets here again) I have two props one for cool-low humidity days and one that is about 1/2 to 1 pitch less for these bad air days. With this in mind I have been able to get most of my lost speed back but some real bad days even that is not going to do it. Tommy Jordan
    Last edited by 2fast4u; 07-09-2007 at 01:36 PM.


  2. #2
    '02GPRider's Avatar
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    Aside from adjusting the carbs, I find that just swapping back to an 87mm nozzle from the 85mm is enough to keep RPM's up in the safe range in the heat.

  3. #3

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    Quote Originally Posted by '02GPRider View Post
    Aside from adjusting the carbs, I find that just swapping back to an 87mm nozzle from the 85mm is enough to keep RPM's up in the safe range in the heat.
    That's a good idea too plus you have better accleration to boot when the motor is down a little on HP from the bad air days of summer!

  4. #4
    2000 GPRXP 4tec shooter98xpl's Avatar
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    maybe I am missing something, but isn't the EFI boat suppose to compensate for the change in humidity? Also, I am still turning my prop the same rpms as I was in the cold days. I am also running at the same speed. Mine has not changed no matter what the weather does. So do I have something wrong or ????
    SHOOTER

  5. #5
    Duke's Avatar
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    Quote Originally Posted by '02GPRider View Post
    Aside from adjusting the carbs, I find that just swapping back to an 87mm nozzle from the 85mm is enough to keep RPM's up in the safe range in the heat.
    +1

  6. #6
    Moderator RX951's Avatar
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    Quote Originally Posted by '02GPRider View Post
    Aside from adjusting the carbs, I find that just swapping back to an 87mm nozzle from the 85mm is enough to keep RPM's up in the safe range in the heat.



    Quote Originally Posted by 2fast4u
    your ski can be off as much as 100-125 rpm's and top speeds off as much as 2-4 mph depending on how bad the weather realy is. When the weather gets this bad and most motors tend to run even richer due to the lack of good cool, dry air.

    tru dat, tru dat

  7. #7
    2000 GPRXP 4tec shooter98xpl's Avatar
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    and what about my statement on my ski? hahaha.
    SHOOTER

  8. #8
    Duke's Avatar
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    Quote Originally Posted by shooter98xpl View Post
    maybe I am missing something, but isn't the EFI boat suppose to compensate for the change in humidity? Also, I am still turning my prop the same rpms as I was in the cold days. I am also running at the same speed. Mine has not changed no matter what the weather does. So do I have something wrong or ????
    SHOOTER
    That doesn't make any sense to me Shooter. Usually we loose 100+ rpms from the 70 degree weather to the 95+ we have now. EFI or carbed. The EFI on the GPRs doesn't have an oxygen sensor so changing fuel curves for temps is pretty limited. Still the cooler the air the more power you make due to density.

  9. #9
    MPower's Avatar
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    Yep, I'm down 100 rpm.


    Shooter, get with the program dude your boat is SLOOOOOOOOOOW

  10. #10
    Drink My Dust's Avatar
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    Quote Originally Posted by 2fast4u View Post
    Just a reminder to everyone! Now that the hot dog days of summer are upon us with temps in the 90-100 range and humidity in the 70-95% range and water temps reaching 90*+ your ski can be off as much as 100-125 rpm's and top speeds off as much as 2-4 mph depending on how bad the weather realy is.

    Example...........a few weeks back we had some real hot humid weather in. I was only able to turn my prop 7120. In one day (over night) we had a cold front come in and we hit the mid 50's and some good crisp air came in.......Da'Judge turned 7230 rpm that morning and I was up 2 mph.........both RPM readings were with about the same level of fuel........and all in less than 24 hours.

    Good air is a terrible thing to miss............

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