08-21-2010, 05:19 PM #1
Ride Plate for Seadoo Pump Conversion - Need Help
I've had the JD seadoo pump conversion since the beginning of summer. I'm having a problem keeping the ski planted in any water conditions and its causing me to come unhooked and hit the limiter. Right now I'm running the Jims modded VX plate and I have tried ever different combination of shimming with no positive results. I can ride in absolute glass conditions and be bouncing around so much that I am getting absolutely frustrated. I've been told that it could be that I'm not an experienced rider. Who knows. I've been riding for 6-7 years but never at these high speeds. If anyone else has done the seadoo pump conversion, please let me know if you are experiencing the same ride as I am. If not, what plate are you running and how have you shimmed it...if at all. Speeds are fun but I need to be under control. I can't even do top speed runs at this point cause I am not hooked up long enough to get to full speed. Let me know what you guys think. Thanks!
08-21-2010, 06:03 PM #2
it has nothing to do with your pump, i tried the vx plate on my fz and in any kinda chop (my pilot) gets smoked by slower ski's... and in smooth water it porposes alot..
the fz's need a stepped sponson design A.S.A.P
08-21-2010, 06:44 PM #3
Do you have the seadoo pump on your ski? If so, what plate are you running now and did it fix the porpoise?
08-21-2010, 07:22 PM #4
I did back to back tests with Jim's VX and the stocker. When I say back to back, I really mean it... like tests 30 minutes apart with nothing else changed.
Jim's VX: 85,7mph on GPS. Trim 1 up, no shim, semi-superman position, 3/4 fuel + 3 gals in the aft fuel cell. Feels good to around 82mph, steady and stable. After 84mph... starts to porpoise very badly to the point of unhooking at maximum recorded speed of 85,7mph.
Stock plate: 83,4mph on GPS. Trim 1 up, shim plate removed and front bolts shimmed 0.090", semi-superman position, 3/4 fuel + 3 gals in the aft fuel cell. Feels good all the way to top speed... had light porpoise at top speed but nothing bad enough to unhook the ski.
So Jim's VX plate was good for +2.3mph on my ski. Very good. However, the unhooking at top speed is indeed frustrating as it prevents going faster. No point of adding more power in my opinion until the hull is tuned better. I have seen top speeds in the upper 86mph on C14 fuel @ 24* timing advance this summer.... but my ski simply unhooks after less than 12 seconds of WOT time -- kills the fun. So I am derating power for now and enjoying an ok WOT stability at around 84mph.
I had an opportunity to run the VX plate in the chops and I totally agree with the comment made above -- the unhooking is so bad that it makes it difficult to race stock skis.
I guess this is all a question of compromise and proper setup for any given riding condition. I am sure there is a way to improve the bouncing above 85mph.... but IMHO, design limitations become more obvious over and above a certain threshold.
In conclusion, I am very satisfied with the VX plate Jim did for me. Numbers don't lie. Next step is figuring out how to smooth the ride in the 85-87mph range.... and that will be a challenge in itself.
08-21-2010, 08:22 PM #5
08-21-2010, 09:06 PM #6
08-21-2010, 09:09 PM #7
08-21-2010, 10:41 PM #8
I have no F'n clue lol. I think I'm gonna try a different plate. Either the R&D or Riva. If I'm gonna porpoise like a mutha with the VX plate no matter what at these speeds then it is worthless to me. I'm gonna try a few more different shims with more going into the back but I don't expect much to change.
08-21-2010, 10:41 PM #9
08-21-2010, 11:01 PM #10
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