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  1. #1
    subparwelder's Avatar
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    P-x rpm question

    I know it has been posted several times but I thought I read about a couple 76-78 mph budget built x boats hitting these speeds by turning over 8100 rpms. I hit 73.2 yesterday at 8060 rpms with 75 deg temp at about 390' elevation and about 3/4 tank or more. Would anyone recomend trying to get another 60 to 90 rpms out of this new prop before the summer heat gets here? If not does anyone see anything i'm missing to get that extra 1-2 mph. I will be thrilled to hit 75 and leave it alone. Thanks for any advice and thanks to everyone on this site for giving me the balls and the know-how to get this bike going this fast. It's scary tearing into a $12000 bike and without this forum I would never have done it myself.


  2. #2
    Having Fun jp1300r's Avatar
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    What are you running your trim at for top speed runs? You need to run 2-3 above neutral trim. I like my r's right at 8100-8120. Depending on the weather BP/TEMPS/HUMIDITY you will lose or gain R's. You will get heat fade in the summer. I run a 160* thermostat and this has reduced heat fade greatly. Have you done a thermostat 160* yet?

  3. #3
    Having Fun jp1300r's Avatar
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    Oh I see you are running a VTS rod maybe? If you are try this, take it off and turn the heim joint end all the way in. Make the rod as short as possible. Try a run one down from the top on the trim gauge. Do this on very smooth water, no small rollers or boat wakes. That R&D filter maybe costing you R's, too. You can try it without back to back to see if it is. If it is use a Spectre SS air filter.

  4. #4
    subparwelder's Avatar
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    I wondered about the r&d filter as well then I asked Danny about it and he told me they flowed the same. I have not done the 160deg thermo yet. I think i'll get my prop turning 8150 and see where i'm at. If I do it now it will probably drop to about 8100-8120 for most of summer.

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