1997 GTX

[HenRock]

Hey everyone,


I’m brand new to jet skis and could really use some guidance. I bought two used ones as a project to work on with my son, who’s been battling depression. I sold my Ducati to get these skis, and while it’s been a steep learning curve, I’ve learned so much about 2-stroke engines. Honestly, the process has been a blessing — it’s therapeutic for both of us.


The problem (GTX):
After a lot of troubleshooting, we swapped in a rebuilt engine. It usually starts (sometimes with a shot of starter fluid) and revs fine on land at about 3,100–3,200 RPM. But the second it goes in the water, it dies. Occasionally it backfires a little on startup.


I haven’t rebuilt the carbs because they looked pretty clean, but now I’m thinking that may be the issue. Could this be carb-related, or should I be looking somewhere else first? This was a full "rookie rebuild" except for the carbs.


Second ski (GTI, same year):
This one runs great, but a bolt on the exhaust manifold snapped. Right now I’ve got it rigged with a washer setup to hold it, but it’s leaking water slowly when running. I’ve tried getting those insanely tough steel screws out with no success — I can’t even explain how they break, they’re so strong. Should I pull the manifold and drill it out properly, or is there a smarter fix that won’t risk making things worse?


Any advice would be hugely appreciated. More than anything, I just want to get these skis running so my son and his brothers can enjoy a good weekend together on the water.


Thanks in advance!

 

[mikidymac]

GTX: Where is the rebuild from and what is the compression?

GTI. You will need to replace the rubber bushings in the lower pipe mounts or it will keep breaking the bolts from vibration.

 

[HenRock]

GTX: Where is the rebuild from and what is the compression?

GTI. You will need to replace the rubber bushings in the lower pipe mounts or it will keep breaking the bolts from vibration.

The engine came from another 1997 GTX, and compression reads about 145–148. The issue is that as soon as it hits the water, it dies.

Regarding the GTI, the bolt broke when I was removing it. It’s holding for now, but I’d like a long-term fix. Short of replacing the manifold, is there another solution? Have you ever dealt with a broken bolt like this, and how did you remove it?

 

[mikidymac]

What is the idle set at?
Have you gone through the carbs?
So it will not start when in the water but will on the trailer?

Stainless in aluminum is a pain to get out clean.
Did it break when trying to remove it?

 

[HenRock]

What is the idle set at?
Have you gone through the carbs?
So it will not start when in the water but will on the trailer?

Stainless in aluminum is a pain to get out clean.
Did it break when trying to remove it?

The idle fluctuates between 2800 and 3400 - I'm not sure why. No Carb it is next; it should have been first. I did look at it, and it seemed fine, but I didn't touch it. It starts on the trailer, no problem. It sometimes starts in the water especially if starter fluid is introduced, but it has really low RPM with gas fully on, and if you let go of the throttle, it dies.

 

[HenRock]

The idle fluctuates between 2800 and 3400 - I'm not sure why. No Carb it is next; it should have been first. I did look at it, and it seemed fine, but I didn't touch it. It starts on the trailer, no problem. It sometimes starts in the water especially if starter fluid is introduced, but it has really low RPM with gas fully on, and if you let go of the throttle, it dies.

I'm not sure if it matters (remember i'm new withj Jetskis) but the hull did flood and that is when all this starter. I did check MPEP and carbs etc.

 

[HenRock]

I'm not sure if it matters (remember i'm new withj Jetskis) but the hull did flood and that is when all this starter. I did check MPEP and carbs etc.

I also saw another post where you suggested it was valve timing and it turned out that was the case. I

 

[mikidymac]

Did you have the rotary valve out/off?

Don't use starting fluid, it is bad for 2-strokes and if it doesn't start without it something is wrong and not going to fix itself.

 

[HenRock]

Did you have the rotary valve out/off?

Don't use starting fluid, it is bad for 2-strokes and if it doesn't start without it something is wrong and not going to fix itself.

no the rotary valve on the GTX was untouched. someone else told me that is what i should do. thank you... I think i will rebuild the carbs maybe adjust the low/high and idle screw first and see what that does. Thoughts?

 

[HenRock]

how do i check if the gas tank has water mixed in?

 

[mikidymac]

You would see water in the water separator/fuel filter up under the dash.

Make sure you follow the Carb Rebuild Thread to the letter.

 

[HenRock]

The GTX carb is running great now — it really needed that rebuild. There was a ton of dirt and debris inside; I can’t believe I hadn’t cleaned them all sooner. All the jets were thoroughly cleaned, and new gaskets installed. The jet ski starts right up now with no hesitation.


That said, I’m still dealing with two issues — one new and one old. The low-speed screws (twin carbs) are set to 1 full turn out from seated, which I believe matches the specs. The high-speed screws are set to zero (with the PTO side just slightly open).


Initially, the idle screw was completely open, and the engine wouldn’t stop running — pretty scary. I had to back it out (counterclockwise) to reset and then adjusted it to idle around 3000 RPM. However, sometimes the RPMs spike way up unexpectedly. I thought it might be a throttle cable issue, but the cable seems fine. Any thoughts on that?


Also, when I first start the jet ski, I still get a single “pop,” and then it runs fine afterward — though sometimes I’ll get a random pop while it’s running too. Could this be caused by water in the fuel tank? I’m running out of ideas. I finally drained the tank — it was filled with 94 octane premium, but I plan to use 87 octane fuel with an additive like Seafoam Marine or Seafoam Restore going forward. What do you think?

 

[burtshaver2021]

The high rpms could be the fuel system sucking in air. Have you changed the o ring in the fuel filter and the fuel selector valve? They are common items that will suck air if old. I run premium fuel in all my small engines and seasonal toys. The premium fuel with no ethanol will store better than the lower grades and I’m never sure when the last ride of the season is and how long they will be stored for. I still add fuel stabilizer when storing them.

 

[etemplet]

If the engine is revving at idle the low speed is lean. Revving the engine after a cold start can result in a runaway. Engines are made to run in the water. Running in the driveway is only good for a start up to make sure the engine runs. As soon as the RPM starts to increase when you are not applying throttle shut down the engine immediately.