Sort of 'go fast' PWC - anybody else?

B

Bruno

New member
I have 5 Jet Skis (yeah, they are all actual Kaw Jet Skis) and I've been playing with 'my' ski for the last year for speed until I feel I got too much and reversed course. In the first 30 hours on my Ultra 250 I've tried numerous impellers, polished the tube, tried several different ride plates, wet bearing setup, different sponsons, added a cold air intake, larger air filter (more air), performance exhaust and have had a local electronic tuner guy work on custom tunes changing several perameters from everything from boost, by fooling other sensors, to raising the rev limiter etc.

It's been fun, and expensive, but after my last 'top speed' run I decided that under 70mph is about all that's safe for a stock hull design on a ski. I've not run with a true GPS onboard, too busy driving, but I got some pretty high readings on the digital speedo before I backed things down. Just wondering if anyone else has played with hot rodding their ski? With nothing but Solas Concorde impellers and Riva ride plates my twin STX-15 Skis both easily hit 65 with 2 passengers on them. That's great for me and plenty for my wife and kids. Besides, if the operator is trigger happy when pulling a skiier, they'll pull the handle out of the skiier's hands and about get knocked off the Jet Ski when the rope and handle come flying back. You know why we know that. :bonk:
 
Hi Brent. Welcome to Net Boat Talk. That is crazy fast for a 250cc ski. I had to wonder if it was a typeo. Maybe the 250 does not represent the cc's of the engine. :confused:
I have a stock Yamaha 700. I will get into the upper 50's and that is fast enough for me on a jet ski.
No one else on here has talked much about them, so I'm hoping your post will draw out a few jet ski folks.
 
Yeah, the "250" refers to the stock factory horsepower rating. It is a 1500cc 4 cylinder with a supercharger on it. Two others I have are pretty well identical but without the factory installed supercharger. I think they are rated at something like 160 horsepower each. My 'little' set are 1100cc 3 cylinder 2 strokers that only put out 120 or so hp. One of them will run 57 and the other just does hit 60. Still a bit fast for kids to play with.
 
Whoa, 250hp. Wow. Heck that will do 70 right from the factory. :thumb: That has to be a pocket rocket. :eek: :D I didn't even know they were making 1500's now. Kewl.
 
Can you overdrive the blower and remap the fuel? Might be fun. But then you'ld probably have to go through impeller and housing mods again.
 
The fuel and boost pressures where changed with some of the software modifications done. Although it's nothing like what is found in hot rod boats, the best estimates are that my ski is putting out about 310 hp. I suppose that does give it a decent hp to weight ratio in what is nothing more than a 10' boat. I'm thinking that a 300 + hp outboard on a 10' jon boat would be a bit of a handful. :biggrin:
 
I haven't owned one....I have owned some mini-jets..my fave for a Bombardier Speedster with the twin 80hp jet drives. 14'6"...0-50 the thing could take most boats. It would nudge 60mph on a good day.

I have spent a lot of time on PWCs...a few modded.

I thought the unspoken rule for PWC manufacturers to sell their products in the States was a top speed of 67mph....nothing allowed past that.

I have ridden some modded ones that would nudge 70....with stock hulls, they do start to get dicey as they pass the 65mph mark.
 
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