97 GTX 787 / 6000rpm

[etemplet]

I'm having the same problem with a 1996 GTX which I only took out once after I rebuilt the carbs and went through everything. On checking things out the water control valve had a very stiff spring so I compared it to another 787 ski. That might not be the problem but the spring was different, thinner so I replaced it.

Something you might want to check is to make sure the butterflies on the carbs are opening all the way. Your raves may be opening but not fully opening.

 

[Travlash]

They'll always rev high out of water, so I wouldn't focus on that. Also, avoid revving it out of water as it can damage your carbon ring. The good news if you damage the carbon ring is that you won't have problems hitting the rev limiter.

If your battery isn't charging, you have a stator, rectifier, wiring issue or maybe a blown fuse. That can't be your RPM issue, though, as you disconnected the red wire.

The 1997 really needs the slotted raves as the rave passages are smaller than 1996. The problem was so bad they made a TSB about it. I hate to tell you to spend $400 on rave valves that may or may not fix your issue, but there's a good chance that's your problem. You say you can hear the raves opening... But I don't hear the raves at all on my 96 GTX. I just get a sudden surge of power from 4-5k RPM and the thing GOES. But maybe one of your raves isn't opening, or opening all the way.

It really sounds like you fixed the carb issue. You could do another spark plug test at WOT to confirm, but probably not necessary. You said you verified that at WOT the butterflies are full open, but I'd double check that.

You could need new spark plugs, wires, or caps, but I don't think that's likely your problem. That said, plugs and caps are cheap and easy to replace. If you do, inspect the ends of the wires and maybe cut a small amount back if you see any corrosion.

It could be a MPEM with a weird failure, but that seems unlikely.

The likely causes are water regulator, mixture/fuel, voltage regulator, and raves. Honestly, it sounds like you've ruled everything out except the raves. I know you say you hear them open, but I don't hear mine and again, maybe only one is opening or they're opening partway. Also you mentioned that the bellows came apart when you pulled them. You may need new bellows, as mine take quite a bit of force to separate and clean. Maybe there's an air leak in the bellows making them malfunction.

I’m going to look into getting new raves for next season. The slotted ones could really help with the RPM? I hear them open at 5k. Because it hangs onto 5k for a couple seconds then they open and it opens up to 6200 before dropping back to 6k

 

[Lothsahn]

Couple seconds?!? The engine should rev straight through 5k like a hot knife through butter. If you have a couple seconds of lag something is wrong.

The only way I notice my raves is if I'm trying to go 35 mph, as my seadoo likes to do 4k or 5k rpm but nothing in-between. I may need to just adjust the raves. There's a screw on top. Apparently tighter adjustments help bottom end up and looser helps top end and transition.

Are your rave valve adjusters flush with the cap? If it's turned in too far, maybe they don't want to come out. Try backing them out a bit and see if it helps.

RAVE valve adjustment ...?

When you do get new rave valves, consider new bellows too if they haven't been changed, since you said the existing bellows came apart easily.

 

[etemplet]

Along those same lines, I have a 1996 I'm helping someone with. It's hitting 6500 RPM now which is a big improvement. I replaced the wear ring and put solas impeller on there because that is what I had in the pile. It hooks up much better with the good impeller but I'm not getting the top end all the way where I think it should be. I may pull the raves all the way out and have a look. I already replaced the piston on one rave and checked out the water control valve. I'm not gonna do much more to the ski. I've done a ton of work already.

 

[Lothsahn]

@etemplet, I'm only getting 6680 at WOT with my 96 GTX and Solas impeller, but I am hitting 54MPH. So it may be that the Solas lowers top-end rpm a bit.

 

[etemplet]

@etemplet, I'm only getting 6680 at WOT with my 96 GTX and Solas impeller, but I am hitting 54MPH. So it may be that the Solas lowers top-end rpm a bit.

Thanks for the heads up on that. The ski has old gas so that might account for some decrease in power. I'm reading only 42mph on the GPS but the bottom needs polishing as the ski sat in salt water for a year. I'm tempted to polish the bottom but it isn't may ski. LOL People have told me that kinda thing matters.

I might get a new Solas for my GTX. Which one did you get??

 

[Lothsahn]

SD-CD 15/23. Overall quite happy with it except I get minor cavitation for 1/2 second at launch and high end rpm is a bit low. That said, I don't know that either of those are the impeller's fault. It was a massive upgrade from my chewed up stock impeller. ;-)

I haven't checked the water valve. I tried to get it off and it wouldn't budge, so I left it.

Also, I get 54MPH according to the sea doo. I really need to do a GPS run...