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IDoSeaDoo

  • Karma: +0/-0
1997 15' Seadoo Challenger Upgrade
« on: March 28, 2014, 05:53:05 AM »
Hey everyone.  I've recently departed from the conventional and am heading toward the awesome, but I might need some help getting there.  I have a small 15' Seadoo Challenger, the old ones with the single rotax 787 110hp engine.  That motor has blown up on me 4 times now and I'll be damned if I'm going to rebuild it AGAIN! It's great in a jet ski, but just too much smoke, consumption, noise, and trouble without the power or reliability.  So I've ripped out that motor and all it's electrical systems.

This winter, I picked up a 2003 Seadoo GTX with a 1500cc supercharged 3-cyl 4-stroke motor making 185hp.  It's set up for closed circuit cooling and runs like a top. My challenge is I have to make this bigger new motor fit where the old one used to be.  In order to do this, I'm going to have to cut out AT LEAST the intake tunnel and glass in the one from the jet ski.  The main reason for this is the thru-hull fitting is not high enough for the new driveshaft to come through. The new engine is too tall, even with the oilpan sitting on the hull.

This presents me with all sorts of questions, like do I glass in the whole half of the jet ski's bottom and change my hull dynamics, do I glass in just the tunnel and then build little pedestals for the engine to sit on, how do I put on a ride-plate?  Do I even NEED a ride plate?

I'm using an old Seadoo XP hull to mock this up, as it has nearly identical dimensions as the boat.  Here's what I have so far:
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Squirrel Master

  • Karma: +7/-0
Re: 1997 15' Seadoo Challenger Upgrade
« Reply #1 on: March 28, 2014, 07:14:03 AM »
Run the jetski toss the seadoo and get a Tahiti ijs  :screwy:
  • Boat #1: 1976 Sleekcraft Kauia
  • Boat #2: 1979 Tahiti Super Tiger
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"most important... WHEN IN DOUBT, THROTTLE OUT!!!"  Crewchief22

rush1

  • Karma: +18/-0
Re: 1997 15' Seadoo Challenger Upgrade
« Reply #2 on: March 28, 2014, 08:51:50 AM »
The old motor ran a smaller pump. When they went with the bigger motor they had to go to a bigger pump because the hp was cavitating the smaller pump

Sent from my SCH-I545 using SoCal Jet Boats mobile app

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IDoSeaDoo

  • Karma: +0/-0
Re: 1997 15' Seadoo Challenger Upgrade
« Reply #3 on: March 28, 2014, 09:52:19 AM »
yep, I'm definitely going with the larger pump. The old pump never put out enough thrust, even with the little 110hp motor.  I'm going to use the driveline out of the jet ski.  The weight difference between the two is only 400lbs (boat weighing 1200lb).  Since I'm not running the stock rideplate, I'm going to have to design my own.  I plan to reinforce it to the hull and not the pump itself to prevent any sort of potential pump damage.  What can anyone tell me on that topic. Shape, length, width, should it be as long as the pump, longer?

Thanks!
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IDoSeaDoo

  • Karma: +0/-0
Re: 1997 15' Seadoo Challenger Upgrade
« Reply #4 on: May 01, 2014, 07:57:18 AM »
Well, I hate to leave threads unfinished, so to due to the lack of interest on this site, I've moved my thread to other forums. Here's a link if anyone cares to see where this goes. Cheers  :beer:

http://www.greenhulk.net/forums/showthread.php?t=213977

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