1996 GTX New motor no top end performance

[96GTXtom]

My son and I just spent 6 weeks on a 96 GTX motor rebuild. The entire engine has been rebuilt by our local shop, carbs rebuilt, and so on...

Got it in the water last week for the break in period and have found that the ski runs great until it warms up. Then it runs good only up to 5500 RPM +/- @ 35MPH. Cold out of the water it will start and rev to 7500 RPM!

So far it has 4 hours of run time and I don't know what to try next? It runs good and starts with no problems but has NO top end once warm. Acts like it is starving for fuel? I have to reduce the throttle and it will run fine up to 5500 rpm only??????

I have done the following.

• Replaced the complete fuel system (prior to installing new rebuild)
• Flushed and replaced all filters and lines on oil system
• confirmed adjustments on carbs 0 and 1 1/2 turns
• set idle in the water to 1500 RPM
• Synthetic oil used
• rebuilt exhaust pipe
• adjusted rave valves full down
• gap set the new plugs
• installed primmer system removed choke plates (due to damage to one choke rod)
• New wear ring
• impeller was checked and reinstalled
• drive unit was alligned with seadoo tool with new shims

Any Ideas????

 

[nswillin]

Tom, I'm kinda concerned about the break in. Proper break in is crucial to your new engine, heat is your worst enemy. If your using the injection system, then you must premix gas 50:1. If not, richen it up to 32:1.

During the first 10 gallons of gasoline, there should be NO full throttle operation. Let the engine warm up for about 10 min then vary throttle up and down but no more than 20% for first half hour. Cool down, then go 50%, cool down 90%. Stay at 90% for the remainder of gas.

 

[timmyboy76]

your carb/s lsa( low speed adjustment) should be set at "1", and i'd double check compression...if good, have mechanic check psi of n/s(needle and seat assy):cheers:

 

[96GTXtom]

Thanks guys. I will check the carbs out again (with a pro). Regarding the fuel. Both my local shops said "No" to the premix gas on the first tank. I want to do the right thing here so if I need to run pre-mix and the injectors also let me know ASAP!
The warm up was done at 0-50% power for the first three hours (half hour at a time). The last hour yesterday was 10 minutes warm up on the lake and yes I was trying to see what it would do above the 3/4 power levels for short burst. It was cooled off and I put it back on the lake for a short burst while cold and it ran fantastic for 2 minutes variation from 0-90% power. After this it will only run to 5500 rpm period. I put it back on the water today and same thing. Great start up and plenty of power available until two minutes of running the motor.

I'll let you all know because I need to get this thing running right after all the time and money into the project!!!!!

 

[cbjrumble]

premix the gas it doesnt even make sense not to on the first tank.