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  1. #1

    Polaris 1200 Powered Jet Boat

    Just thought I would share my Polaris 1200 Di Powered jet boat I built. This site was a huge help in getting this motor somewhat figured out. I have had quite a few issues with the engine right off the bat but I am hoping things are on the up and up! Here is a recent camping/fishing trip I had the boat on. Only access to this place is by float plane, I am not sure, but believe we were the first ones to run jet boats all the way up.

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  2. #2
    Click avatar for tech links/info K447's Avatar
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    What RPM are you running at wide open (when there is actual water under the boat)?

    Sounded like it was bouncing off the rev limiter in portions of the video.

  3. #3
    Yes it was hitting rev limiter on that corner, I had a few rocks stuck in the intake grate and had nowhere to stop to get to the stomp grate at the time. I needed to be back on step as shallow stuff was soon approaching! Generally WOT with a clean grate is about 6400 RPM. Is that ideal? I had to hand fabricate a new intake from aluminum and an intake grate from T1 steel. Intake grate gap is 3/8" and was obviously oversized to account for the amount of restriction. Hoping my calculations were right. I do not hit rev limiter with a clean grate unless I am in some rapids where I loose suction. With the 10 degree deadrise it is easier to loose suction than the deeper angled jet ski hulls.
    I am running the nujet impeller in it, as it was the least expensive and the boat had already sucked me dry

  4. #4
    Click avatar for tech links/info K447's Avatar
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    6400 RPM is getting fairly close.

    I forget what my red Virage TXi 1200 Polaris engine would turn.

    Something around 6700-6800 is probably the optimal target zone.

    That said, your impeller is probably going to see some wear from the gravel and sand going through. As it wears and the blade to wear ring clearances increase the RPM might rise?

  5. #5

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    Nice build. That thing needs a BBC or SBC and a berk pump.

  6. #6
    It seems to me a little slow on the rpm range, but you are correct they will rise as the impeller wears, and the impeller will go south very quickly if I am not careful!

    Quote Originally Posted by K447 View Post
    6400 RPM is getting fairly close.

    I forget what my red Virage TXi 1200 Polaris engine would turn.

    Something around 6700-6800 is probably the optimal target zone.

    That said, your impeller is probably going to see some wear from the gravel and sand going through. As it wears and the blade to wear ring clearances increase the RPM might rise?

  7. #7
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by TJS0712F View Post
    ... That thing needs a BBC or SBC and a berk pump.
    Those boats are built to be light weight with very shallow draft.

    A large heavy engine would not match the design goals.

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  9. #8
    Quote Originally Posted by K447 View Post
    Those boats are built to be light weight with very shallow draft.

    A large heavy engine would not match the design goals.
    The boat in the background of a couple of those pictures was built by my friend at the same time I built mine. He put a Yami SVHO motor in it. Thing hauls ass! I think it is just below the edge of being too heavy for the hull design though.

  10. #9
    Connecticut CrazyA's Avatar
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    Awesome..... just awesome!!!!

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