Sea Doo 720 options

RaWarrior · 03-01-2010, 06:02 PM

Hey all, I used to have an account here but apparently a year or two of inactivity got it deleted. Anyway, I have a '99 Sea-Doo GTi with the 720cc motor. It's got a lot of hard hours on it, and the motor is just getting tired....hard to start, smokes a lot more than it used to, overall lack of power. I seem to remember the compression was just a tick over 100. It's barely hitting 43-44mph, a couple years ago it was good for 49-50. This spring I'm planning to do a fair amount of work to bring it back to like new, if not better. Motor rebuild/improvement, new prop/pump rebuild, possibly new grate/ride plate. The exterior is clean, and it's got new custom seats from a local upholstery shop, plus I really can't afford to buy a new one.

1. What should I do to "freshen up" a high-hour motor? Rings, pistons, ports, hone cylinders?

2. I've looked into the Group K kits for this motor. However, they don't respond to emails and nobody answers when I call. Are they still in business? While I realize that a 720 in a 3 seat hull will never be a rocket, a little boost certainly wouldn't hurt.

3. I've been offered my neighbor's 2000 GTX with the 950cc motor for free. It's pretty beat(absolutely zero maintenance, ever), and sank at the dock the same day it was launched last summer for unknown reasons- it's been on the trailer ever since. However, when I went over to their house to check it out, it started surprisingly easy and seemed to run fine, at least on the trailer, so the motor isn't toast. How difficult would it be to swap that motor into my GTi? I'm sure even a stock strength 950 would be far more powerful than even a hopped up 720- or would it? If the mounts are the same I would consider it, but I'm not confident enough with glassing to modify/make new ones.

I'm pretty open to any suggestions, other than "buy a new one".

Thanks for any tips or advice.

vshockey10 · 03-01-2010, 06:10 PM

fix the hull for the 951 or look for a new hull and transplant the 951 in.. sell your 720

nightrider05 · 03-01-2010, 08:15 PM

Quote:

Originally Posted by vshockey10

fix the hull for the 951 or look for a new hull and transplant the 951 in.. sell your 720

Where did it say the hull needs fixed? From what I read, its just a beat on 951 GTX..

I personally think you should take the GTX for sure...its parts alone are worth nearly what your seadoo is together. Go through and fix it all up and ride it like it was stolen(which..getting that for free is a STEAL!!)

On your ski..I would disassemble it and see what all needs replaced. May just need bore, new rings and pistons. Then, as long as the 951 GTX is running great, sell your ski.

Spend the money you make off your ski on gas for the next few years of riding!

vshockey10 · 03-01-2010, 08:21 PM

he said it sank.. so I assumed unless he forgot to put the plug in there is a crack somewhere

RaWarrior · 03-01-2010, 08:57 PM

I don't think the leak is due to the hull itself. When I looked at it I crawled under and looked for any big damage. The keel was kinda dinged up, but all just gel damage. Nothing major enough to warrant a leak. Otherwise it looked clean. My guess on the leak is probably due to it never being winterized in upstate NY. Maybe a burst hose below the waterline, or some leaking in the pump? Would the engine even run if a jacket had burst in the motor? When I started it a hose was hooked up to the barb next to the pump.

When I said beat, I meant borderline destroyed. Seats are trashed. The speedo and the digital gas gauge are both dead, with the info screen all messed up. The formerly rich red gelcoat is now faded to almost pink, and all the plastics are gray and brittle. The reverse handle is seized to forward. Throttle and choke were both sticky. Steering was very stiff. A couple bolts were missing(looked to be snapped off) on the grate and ride plate...odd, because I don't know that anybody has ever worked on it, but he did buy it used in '02 I believe. It would need A LOT of work to bring back to a "daily driver" condition....pretty true because I often did ride my jetski to work(I work at a marina doing online sales and stuff)

I really don't want to get into a big restoration project, which is what I'm feeling like it would turn into. Like I said, several people use this boat and it needs to be as reliable as can be expected. I sorta know the guy that owned it. Nice guy, but is the "push the button and it magically moves" type...had no idea what went on under the seat. As such, treated it as a toy leading to it's current sorry state. Now he just wants to get it out of his driveway, doesn't want to spend money to fix it.

Meanwhile my '99 looks practically brand new. It's metallic purple hood was always waxed, new seats, and was always covered when not in use. I guess that's good for sale value though. What do you think it's worth as-is? It's totally functional(other than it's speedometer is kinda odd---it randomly jumps around whenever the tether is plugged in). Runs, just not that great. Maybe 2 grand?

I guess it's an option, but I have a feeling it would turn into a big money pit if I tried to fix it up. But then again, compared to probably a grand to "renovate" my 720 with new motor, new pump, ect it might not be bad.

I figured a budget of about a grand, for whatever I do. 720 rebuild, motor swap, or fix up the GTX. I've seen lots of threads about 580's to 720s, and 720's to 787's. Nothing about the 950 thou.

I'm sure I'll take the GTX, just a matter of what I'll do with it. Sell it as-is? Part it out? It's got a decent trailer under it also.

The Greygoose · 03-02-2010, 11:27 AM

You might want to post this in the SeaDoo section-welcome back!