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  1. #1

    46 mph @ 7600 RPMs - C180

    I have a totally stock boat other than SS wear ring, a 13/18 Solas and filled rideplate holes (really did give me 1-2 mph up top )

    Now, granted, there are only 5 hours on the boat (according to the meter, and I understand those are a bit generous)

    I am getting 46 mph @ 7600 RPMs. Should I repitch the 13/18 to get to 8100...or throw the stock impeller (10/21) back in...or add mods.

    I have no freaking clue and I hope the kind folks here will help me out.

    Thanks guys.


  2. #2
    What kind of ski do you have?

  3. #3

    Challenger 180

    07 Challenger 180...boat.

    You ski guys have a TON more knowledge on modding and I figured I would ask here about how to raise my RPMs up 500.

  4. #4
    Moderator RX951's Avatar
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    This thread has been moved to the sea-doo sport boats forum

  5. #5

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    It's tough modding the boat in the first ten hours, because the engine changes a lot in that time. Especially a prop, in which you're really trying to match with the engine's current output. I put a 13/18 on at the 10th hour, because I knew the engine wasn't going to change as significantly past that point (except for my own modding), and it made the RPMs jump from the stock prop's 7950, right to 8100.

    My advice would be to go back to the stock prop for a few more hours, to let the engine break in, to get a good baseline as to how you are running with the stocker, and ensure that you're not having any other issue causing the low RPMs. I just couldn't imagine that you'd have to take pitch out of a true 13/18 prop; that's a relatively "low gear" prop. The 13/18s don't come with the "R" pitchblocked designation, and I can tell you that two of my blades were originally off by more than a millimeter from the others. It's possible that you might have a blade or two that needs to be de-pitched before you put the 13/18 back on.

    Finally, you're a fellow Floridian, and I can tell you that this heat will kill a good 200 to 300rpms. Huge difference in 90 degree water and 70 degree water running through the intercooler. I can't wait to throw a 15/20 prop on this "winter" on be running well over 60mph.

  6. #6
    1996 Sea Doo Challenger (787x1)
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    Quote Originally Posted by clpsuite View Post
    I am getting 46 mph @ 7600 RPMs. Should I repitch the 13/18 to get to 8100...or throw the stock impeller (10/21) back in...or add mods..
    I'm new to boats...AND jet boats---just got my 1996 14.5' Challenger in August.

    I'm currently about done with breaking in a fresh SBT 787cc rebuilt 2- stroke engine (rated at 110 HP), and I've gotten GPS speeds of 45 MPH, with (old) stock impeller and (old) beat up wear ring.

    On some other forums, guys have said 45 MPH is about what my boat should be doing, if all's well...just a benchmark for you to work from.

  7. #7
    If shes got boobs or a throttle, I'm on it! badvinny's Avatar
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    Quote Originally Posted by Steve762us View Post
    I'm new to boats...AND jet boats---just got my 1996 14.5' Challenger in August.

    I'm currently about done with breaking in a fresh SBT 787cc rebuilt 2- stroke engine (rated at 110 HP), and I've gotten GPS speeds of 45 MPH, with (old) stock impeller and (old) beat up wear ring.

    On some other forums, guys have said 45 MPH is about what my boat should be doing, if all's well...just a benchmark for you to work from.
    Two totally different boats, 2 stroke vs 4 stroke, ...

  8. #8
    I am running a 14/19 in my 06 c180 and am slightly over 50 mph with much improved holeshot, BUT... I live in Nova Scotia Canada and the water temps around here never get anywhere near what they do in FLA.

    If you dont have a custom air intake yet you need to do that now as just that mod alone got me a solid 300 rpms. My intake was very simple as well. Just take the rubber hose connected to the supercharger, remove the clamps from both ends, turn it around and clamp the opposite end to the SC so it points straight up and attach a K&N filter to the open end.

    I would also follow VX1,s advice and check your impeller blades to make sure they are all the same pitch.

    Good luck and let us know how you make out as there is not much info on modding boats so every little bits counts.

    Oh yeah... dont forget to change the ceramic SC clutches to metal ones from Riva Racing. Seriously dont start the motor again until the ceramic is outa there!!!!!!!!!!!!!!!

  9. #9
    Quote Originally Posted by cfnnslsq View Post

    If you dont have a custom air intake yet you need to do that now as just that mod alone got me a solid 300 rpms. My intake was very simple as well. Just take the rubber hose connected to the supercharger, remove the clamps from both ends, turn it around and clamp the opposite end to the SC so it points straight up and attach a K&N filter to the open end.

    That piece of great info. will save me a couple hundred bucks in the spring

    Thanks
    Mike

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