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  1. #1
    mikevv's Avatar
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    First try at prop bending

    I decided to bend the prop on my SHO and having heard the stories of how hard it is to remove the prop from the driveshaft I decided to try and bend it while it was still on the shaft to save time. I had to make a tool to fit over the trailing edge because the usual 24 inch Crescent wrench was just too big. As you can see in the attached pictures I used four long bolts thru the pump and clamped it in a large vise. It held everything together well and bending the prop the two degrees I needed was easy.

    FWIW The stock 12/19 was actually a 14/20. I bent only the trailing edge to get 14/18 for my first pass at this. If I understand correctly I should get maybe another 200 rpms.


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  2. #2
    Moderator beerdart's Avatar
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    Looks good nice job on the tool I use an old driveshaft with a slit cut into it.

  3. #3
    lets race.... mikeFZR's Avatar
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    Nice job I never pitched my stock prop, but I picked up exactly 200rpms by decreasing the trailing edge of my skat by 2 degrees.

    By the way, those gauges look fimilar

  4. #4
    Kristian Keppel Waterholics's Avatar
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    So 1 degree or one mm is = 100 RPM's ? Mike this prop bending thing is looking more and more usefull everyday. I think I may just order a gauge and practice on my stock prop first and then on my skat.

  5. #5
    lets race.... mikeFZR's Avatar
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    Quote Originally Posted by Waterholics View Post
    So 1 degree or one mm is = 100 RPM's ? Mike this prop bending thing is looking more and more usefull everyday. I think I may just order a gauge and practice on my stock prop first and then on my skat.
    1 degree = 100rpm is a rule of thumb. Mods, tempature, rider weight, etc all effect it. Prop bending is easy once you get the hang of it. Just takes a little patience. And having a "junk" prop to test on first is a great tool to use.

  6. #6
    mikevv's Avatar
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    Quote Originally Posted by mikeFZR View Post
    Nice job I never pitched my stock prop, but I picked up exactly 200rpms by decreasing the trailing edge of my skat by 2 degrees.

    By the way, those gauges look fimilar
    The gauges are sweet! Makes the whole thing easy and repeatable.

    So what is the rev limiter set at on a stock SHO?

  7. #7
    lets race.... mikeFZR's Avatar
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    Quote Originally Posted by mikevv View Post
    The gauges are sweet! Makes the whole thing easy and repeatable.

    So what is the rev limiter set at on a stock SHO?
    There are 4 different stages for the SHO/FZ rev limiter. Stage 1 cuts spark/fuel to cylinder #1, stage 2 cuts spark/fuel to cylinder #2, etc. This is all starting at 7800. I would recommend pitching to run at 7700-7750. Personally, I run at 7640.... but I have a few ideas to get my rpms up.

    Also, there is essentially a "floating" rev limiter on the stock/reprogramed ECU which will limit your rpms if the ECU senses a rapid increase in rpms. I.E. holeshot or unhook.

  8. #8
    steved's Avatar
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    Quote Originally Posted by mikeFZR View Post
    There are 4 different stages for the SHO/FZ rev limiter. Stage 1 cuts spark/fuel to cylinder #1, stage 2 cuts spark/fuel to cylinder #2, etc. This is all starting at 7800. I would recommend pitching to run at 7700-7750. Personally, I run at 7640.... but I have a few ideas to get my rpms up.

    Also, there is essentially a "floating" rev limiter on the stock/reprogramed ECU which will limit your rpms if the ECU senses a rapid increase in rpms. I.E. holeshot or unhook.
    There is also a boost limit that closes the throttle we ride in colder condition we see the boost limit just before 7700 it closes the throttle and we get 7680 but this is not spoken about much for some reason. We can re pit the prop or change nozzle size but the magic number is 7680.

  9. #9
    lets race.... mikeFZR's Avatar
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    Quote Originally Posted by steved View Post
    There is also a boost limit that closes the throttle we ride in colder condition we see the boost limit just before 7700 it closes the throttle and we get 7680 but this is not spoken about much for some reason. We can re pit the prop or change nozzle size but the magic number is 7680.
    Good info. Also, the boost limiter will only kick in if the air pressure is greater than 145kPa AND engine speed is greater than 7,550 rpms. This is directly from the service manual.

  10. #10
    abracadabra's Avatar
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    So I can essentially run 14 LBS at let's say 7,500 RPMS and the boost limiter won't be a problem? Interesting, Julio...

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