97 GTX 787 / 6000rpm

[Travlash]

Hello all.
seadoo gtx 787 won’t go passed 6000 rpm at 43 mph. New top end. 145 compression.

water regulator was leaking, so i replaced that thinking that is what caused the low Rpm. Still the issue. Wear ring is good.

then i checked rave valves. Cleaned them both up and adjusted to stock.

so now i am stumped. What can cause this type of behavior. Should i pressure test the carbs.
Thanks for any input

 

[etemplet]

Are you sure the water control valve is working properly?

I'd check the rave valves also. Did you replace the bellows? Some are really stiff compared to stock. Not sure if they would prevent full opening but ya never know.

Exhaust hose separation internally. To name just a couple. Good Luck !

 

[Travlash]

Are you sure the water control valve is working properly?

I'd check the rave valves also. Did you replace the bellows? Some are really stiff compared to stock. Not sure if they would prevent full opening but ya never know.

Exhaust hose separation internally. To name just a couple. Good Luck !

Raves are good. Valve is working correctly. Just took it apart and really looked at it and buttoned it up. How would i know if exhaust hose separated internally, can i bypass the regulator?

 

[etemplet]

If you feel the hose you might be able to tell if it has a soft spot. I found this bad on my personal ski. The internals were separated and probably inflating due to exhaust flow and causing a restriction. I can't figure anything that would cause a specific 6K RPM problem. That is an odd range to me and would send me back to basics. What do the spark plugs look like?

 

[Travlash]

Spark plugs are a nice brown

 

[Travlash]

Spark plugs are a nice brown

I’m going to send pictures of the reg valve set up in a little bit

 

[etemplet]

Don't forget to look at the simple stuff.
Is the correct impeller on the ski?
Are the carb butterflies opening all the way?
Are the chokes adjusted properly?
Is there fresh fuel in the ski?

 

[Travlash]

I have had this ski at 53 mph before. Top end went. Broke it in correctly (took forever) .. no only like 5900-6000 rpm hitting 42. I unplugged the rectifier to make sure it wasn’t that and nothing changed. These are pictures of the water regulator. It’s leaking from that little hole

 

[mikidymac]

The lower clamp is rusted as is typical. If it is leaking water then it isn't working correctly.

 

[Travlash]

The lower clamp is rusted as is typical. If it is leaking water then it isn't working correctly.

Yes but from where

 

[etemplet]

In picture 6, the last picture you have the part in your hand that is likely leaking. I think @mikidymac uses an o-ring to seal that cartridge. I have used Ultra Gray to seal it but I like the O-ring idea. My expectation for a 787 with a fresh engine is 49-50mph on the GPS with around 6850-6900 RPM. Not saying they won't go faster but I really haven't seen it.

 

[mikidymac]

The housing deforms and goes bad. The recommended fix is to replace the entire thing but I’m too cheap, lol. So I install an o-ring in the groove to stop the leaking. But if the bellows are bad they have to be replaced first.

 

[Travlash]

I’m going to try that o ring idea and put some Vaseline around it. I was thinking it needed an o ring as the bottom plastic seemed to be bigger than the valve cylinder that you circled. It didn’t seem to set in there tightly

 

[mikidymac]

Use silicone grease. Vasoline is petroleum and can ruin rubber o-rings.

 

[etemplet]

Frickin Vasoline ?? !!! $%&# !! Bring that shiznit with you when you buy parts from the Seadoo Dealer. No place for it on a Seadoo. Use what "miki" said. LOL

 

[etemplet]

The recommended fix is to replace the entire thing but I’m too cheap, lol.

I like ca way you thank ! You Cajun Material. LOL

 

[Travlash]

I like ca way you thank ! You Cajun Material. LOL

So an update. I added a o ring. Went out on the river. Off the bat hit 6800 and 53. Super happy. Went over to the dock and waited for my buddy. Turned it back on 5 min later. Sits at 6000 rpm again. Regulator is no longer leaking. What should i look at next ? The raves look fine. It’s not the rectifier. I have good spark

 

[etemplet]

Next time you take it out try that again and see if you get the RPM that high in the beginning of the ride. You can try unloading the impeller by jump your buddies wake. See if the RPMs come up.

Seems like you might have a fuel delivery problem. If you're running rich the engine has to burn off the excess before it can transition properly. Did you set the Pop-Off on the carbs? They like 38psi. Carb Seats could be leaking. Don't remember if you pulled the choke at 6k RPM to see what happened. Ease the choke out. It will likely bog the engine. Good Luck.

 

[Travlash]

Next time you take it out try that again and see if you get the RPM that high in the beginning of the ride. You can try unloading the impeller by jump your buddies wake. See if the RPMs come up.

Seems like you might have a fuel delivery problem. If you're running rich the engine has to burn off the excess before it can transition properly. Did you set the Pop-Off on the carbs? They like 38psi. Carb Seats could be leaking. Don't remember if you pulled the choke at 6k RPM to see what happened. Ease the choke out. It will likely bog the engine. Good Luck.

I was going to pressure test the carbs next. I also don’t have a choke. It is also pre mix and I’m running 40-1

 

[Travlash]

I was going to pressure test the carbs next. I also don’t have a choke. It is also pre mix and I’m running 40-1

When i unload prop of a wake, it hits 6800 with ease

 

[etemplet]

I was going to pressure test the carbs next. I also don’t have a choke. It is also pre mix and I’m running 40-1

If your Pop-Off pressure is low the ski will run rich and have issues with the transition to the main jet. When you hit your top speed that was all the main jet. I've not experienced a ton of skis but I've not had a 787 have carb issues at 6k RPM. Not that it can't happen, I'm just stumped of what it could be. Usually the carbs have trouble below 5k.

Having a 1997 GTX your ski is a candidate for the slotted rave valves and replacment of the Rave Housings. My wife's ski is a 1997 and when I did that to hers.... it ran great!!

The Technical Service Bulletin or whatever Seadoo Calls it is posted on this forum. (TSB 97-20) Check it out. I had it but my computer crashed last year. LOL

 

[etemplet]

Check this thread. Performance Issue

 

[Travlash]

If your Pop-Off pressure is low the ski will run rich and have issues with the transition to the main jet. When you hit your top speed that was all the main jet. I've not experienced a ton of skis but I've not had a 787 have carb issues at 6k RPM. Not that it can't happen, I'm just stumped of what it could be. Usually the carbs have trouble below 5k.

Having a 1997 GTX your ski is a candidate for the slotted rave valves and replacment of the Rave Housings. My wife's ski is a 1997 and when I did that to hers.... it ran great!!

The Technical Service Bulletin or whatever Seadoo Calls it is posted on this forum. (TSB 97-20) Check it out. I had it but my computer crashed last year. LOL

No the raves aren’t slotted. I have no idea where to look next. I can hear the raves open at 5k. Then they jump to 6 and level out there.

 

[etemplet]

That technical service bulletin I quoted is the one that tells you what you need to do to the 1997 models. Might be worth while looking into. If it was mind I wouldn't give it a second thought. My wife's GTX "Woke up" when I made the changes recommended in the bulletin.

 

[mikidymac]

Do you have the stock airbox and lid?
How did they remove the choke?

Are you still supplying the rotary gear cavity with oil since using premix?