1996 GTX problems

[Shadrack]

Hello guys, i'm new to this forum and I apologize if I have some repeat questions. I've tried searching for previous threads, and a few kind of answered some of my questions. However, I have several questions, and I guess i'll just number them for ease of replying to. Thanks for your all's help!

Okay, I have a 1996 Sea-Doo GTX, with the 900cc 110hp motor. It had 92 hours on it when we got it. We had the engine rebuilt (by SBT I believe) somewhere around 110 hours, about 2 years ago. We have now 140-145 hours on the motor and have no unwanted noises from the motor. We did the proper break-in by the book and it sure felt like it ran a LOT stronger than our old motor on the top end. ( We had the motor installed by a dealership, just so you would know. ) Since we got the ski 4-5 years ago it NEVER had any low end at all. It was a pure dog. It spits and sputters at low rpms (2000-4500 rpm) still today and just doesn't have the "get up and go" like other skis that i've rode. We just replaced the RAVE valves with brand new ones and made sure they were properly installed. It helped it run a lot smoother but it STILL has no low-end whatsoever. On our old motor I could hit 63 mph according to the speedo, now with the new motor it will not hit above 52 mph and the engine revvs to about anywhere 6000-6500 rpm depending on water conditions, before the rebuild i'm pretty sure it was closer to 7500rpms. The dealership said they tuned the carbs and the motor does run very smooth at idle and at WOT. But here's the symptoms.
When holding half/ 3/4 throttle, or any throttle really above 2k rpm besides WOT, the RPM's jump and the ski lunges and falls back slightly. It's not bad, but you can sure feel the power jump for that split second and it does it about every 10 seconds or so. I cannot figure it out at all. Also, at idle in or out of the water there is a loud rattle/vibration sound that seems to be coming from the impeller area. I climbed underneath the ski and the shaft is rock solid and there is not one chip off the impeller. I can't seem to find where the noise is coming from, and it's done that since we've had the ski. Since the new motor was installed, it has been fogged and flushed after every use, just recently switched to high octane gas in hopes to fix the sputtering, and Sea-Doo mineral oil has been use (However, I do have 10 gallons of synthetic oil, but was advised not to use it?).

1. What would cause the RPM jumps?
2. Is there any adjustments to the RAVE valves for more perfomance? Like the red screws on the top of the valves?
3. What is the purpose of the valve on the waterbox? It's never been taken off or fooled with from what I can recall.
4. Is the rattle/vibration noise that I hear normal on this model?
5. And, i'm wondering if there is any performance upgrades (which i'm sure there is) for this model. I'm new to the jet ski performance stuff. Where can I get and what all can I get to increase performance (not wanting to spend over $400-500). I'm wanting to upgrade so I can keep up and SMOKE the newer ski's out there! hehehehehe

Thanks again for your help, sorry for such a long post.

[polaristriple]

Re: 1996 GTX problems

Have u checked the fuel filter? Are the carbs dirty? Whens the last time you put new spark plugs on? Are the jet settings set right on the carbs? Performance mods... I would suggest a new intake grate such as R&D, or WORKS. An intake grate will improve handling, and "hook-up", and will also increase speed over choppy conditions. Also you could put in a better impeller. You could get a SOLAS Concord which will give you drastically better acceleration. And you might want to replace the wear ring, and change the pump oil.

[1fastski.com]

Re: 1996 GTX problems

the rattle is normal { when it stops you worrie }

if you have a SBT engine in there and replaced the rave valves you might run into a problem if they were not cut for the over bore and they could hit the pistons { i assume they were cleaned not replaced }

if the engine does not perform as it should it needs to be tuned by somone who knows how to tune , { just becouse a dealer did it dont mean it was done right }

you can play with the rave settings but it wont do much , the valve on the exhust could help or hurt depending on if its working right .

get the engine running right before any performance mods are done BUT the best bang for the buck is flam aresstors and a rejet then prop that would do wonders if you get everything running right , your engine should run at 6950/7000 rpms stock

[polaristriple]

Re: 1996 GTX problems

The rattle is normal, sounds like metal to metal contact at times...but its norma, and there is nothing to worry about. both of my skis make the same rattle, especially when i jump them out of the water.

[jandrew]

Re: 1996 GTX problems

Yea, I'd go thru the carbs & have them rebuilt. You said the dealer "tuned" them, so that sounds to me like he didn't have them apart.
The rattle is normal. SD makes a spring kit for the pump assy that will take that out, but it's not necessary in my opinion.
Higher octane fuel only costs more and doesn't improve the performance.
You should be using synthetic oil in that ski. The rotary valve needs special lubrication from what I understand. Any fully synthetic "low ash" oil will work, but you must make sure the old oil is completely gone or cleaned out. They talk about that subject all over this forum.

I dont think you could add ANYTHING to that ski for $500 that would make it smoke a new 1200 supercharged! ;]

[Shadrack]

Re: 1996 GTX problems

Well, I know I wont come close to the new supercharged ski's. I'm in love with the new RXT. 215hp!!!!!!

I mainly just wanna be faster than the other 3seater waverunners, etc., I can keep up with them, but they slowly pull away. :emoticonr On my old motor, I could leave them sitt'n, and even stay right beside a 2 seater with the same engine mine has!


I changed plugs two weekends ago, and they sure was nice and black when I changed them. The plugs were a year old. I've been reading about the spark plug wire snip or something like that? What is that, and what does it exactly do?
I'm glad the rattle is normal, that makes me feel a lot better. But as for the rave valves being replaced, I just got the new rubber boots and plastic caps (since one cracked and broke). The actual metal valve is the ones that the dealer or SBT had in the motor I would assume.

I guess I can take the carbs off and clean them really good. I would take it to someone that knows what they are doing, but I live in Eastern Kentucky and that's not going to happen, haha.
If I changed props wouldn't I have to sacrifice top speed? 60-65 mph is plenty fast enough for me, but I love having low end grunt when I want to take off! The carbs could be the problem, but like I said, I don't know much about these ski's yet. Why wouldn't the motor revv on up to 7k?

Do I have to remove the pump to change the oil, what kind of oil should I use, and how hard of a job is it. I'm taking it out July 4th weekend and I'm going to be up against my cousins 2003 Waverunner.

[Shadrack]

Re: 1996 GTX problems

If I got the carbs rebuilt do you all think that would fix my spitt'n a sputtering and gain back my low-end? I guess the carbs has never been rebuilt, just "tuned" by the dealer, so they said anyway. But it does run smooth at idle, i'll give them that much. :emoticont

[frankey01]

Re: 1996 GTX problems

Tuning has nothing to do with cleaning and rebuilding when you tune you are only dialing in your high and low speed screws when you rebuild and clean and tune then you are replacing diaphrams that wear out and gaskets that wear out and cleaning internal filters that clog and affect performance and fuel delivery. I would bet you could change the pump oil yourself there is a tech article here on exactly how to do it and you can use 90 synthetic oil or seadoo has pump oil for about 9.95 a bottle that does three changes I believe. As far as the carbs if you want the ski back for July 4th you better work fast on finding someone if you arent going to do them yourself. They will not have it done in time, the dealer that is.