1997 GTX struggles to rev past 4500 rpm

[87Magnumii]

I’ve got a 1997 GTX that I bought last year. Was supposed to be a running ski when I got it but that’s not been the case. It starts easily and idles perfectly both on the trailer and in the water. The issue is under load it only wants to rev to about 4500 RPM, unless you jog the throttle or hit a wave and the pump breaks free, then it will slowly get into the 6500 range but as soon as I let off it’s back to being sluggish.

Both cylinders have good compression. All fuel lines and filters replaced with new. Both carbs rebuilt with OSD back to OEM kits. Pop off pressure is in spec. Ive tried unplugging the rectifier. I’ve tried adjusting the water box valve. Nothing makes it any better. I’m at a loss if anyone has any ideas.

 

[Rabid]

Can it be the jet pump bearings going bad? Its easy to pull it. You will need a special tool to pull the impeller.

 

[87Magnumii]

Can it be the jet pump bearings going bad? Its easy to pull it. You will need a special tool to pull the impeller.

I guess anything is possible but it free revs pretty smoothly on the trailer with no noticeable noise or anything out of the ordinary

 

[Ckrawiec]

I guess anything is possible but it free revs pretty smoothly on the trailer with no noticeable noise or anything out of the ordinary

FORGET about anything the ski does on a trailer.....running on the trailer tells us virtually nothing other than "it runs".

CHAMP on the trailer, CHUMP on the water - embrace that saying .

If the machine starts and runs, but will only REV to 4500 at max throttle or slowly creep it's way up to higher revs (on the water), you MOST LIKELY have a fuel delivery issue.....time to service the carb(s), even IF they have already been serviced.....the carbs are the heart of the machine and they are persnickity to say the least.....they need to be spot on to extract the full performance out of the machine....I've fiddled with my carbs "multiple" times until I finally got them dialed in just right......I can take those things in and out of a ski in 10 minutes now, I've done them so many times.....

Unplugging the rectifier doesn't do anything but deprive the ski of its own generated electric power (assuming the RECT and Magneto are working properly to begin with). A simple test is to get the ski running and see what the voltage is at the battery....it should be near 14VDC (pretty steady reading) if the ski is generating its own power and sending it back to the battery.

 

[AKnarrowback]

One possible cause for what you are experiencing. The symptom of getting it to rev to full rpm's if you play with the throttle or unload the motor over a wave is typical of how the machine will run.if you need to look into the rave technical service bulletin. Good luck and let us know how things are going.

 

[emspjay]

I agree with AK it could be the Rave's.

 

[BGS]

You did not mention new spark plugs, they eat them. Cheap always do first.

 

[Jtamaro]

FORGET about anything the ski does on a trailer.....running on the trailer tells us virtually nothing other than "it runs".

CHAMP on the trailer, CHUMP on the water - embrace that saying .

If the machine starts and runs, but will only REV to 4500 at max throttle or slowly creep it's way up to higher revs (on the water), you MOST LIKELY have a fuel delivery issue.....time to service the carb(s), even IF they have already been serviced.....the carbs are the heart of the machine and they are persnickity to say the least.....they need to be spot on to extract the full performance out of the machine....I've fiddled with my carbs "multiple" times until I finally got them dialed in just right......I can take those things in and out of a ski in 10 minutes now, I've done them so many times.....

Unplugging the rectifier doesn't do anything but deprive the ski of its own generated electric power (assuming the RECT and Magneto are working properly to begin with). A simple test is to get the ski running and see what the voltage is at the battery....it should be near 14VDC (pretty steady reading) if the ski is generating its own power and sending it back to the battery.

Highly agree, it’s nothing more than your high needles requiring a slight turn in adjustment.

 

[POPPS]

did you rule out the compression?,,,is the battery load tested?