96 Seadoo Challenger won’t rev past 5500 rpm

[Phuck_boi]

I’ve spent hours browsing this forum and people do not post conclusions of how they fixed this issue. Boat intermittently hits 6800 rpm and now I cannot get it past 5500. It will get on plane and hit over 30mph but when it runs like it’s supposed to it’s closer to 6800 at 45mph. I’ve rebuilt the pump, overhauled the fuel system, rebuilt raves with slotted valves and new bellows/o-rings, compression is 145mag/155pto (not sure if this is an issue), flushed oil system it had clear oil in it, not sure wtf it was, now running appropriate Seadoo oil and cleaned the power valves, set oil flow and has a fairly new oil injector, rebuilt carbs with mikuni parts, put new o-ring in fuel filter. Could this be a fuel pressure issue? I’ll choke it when it’s flattened out and it immediately kills it, plugs appear to be burning correctly. Stumped, my friend thinks it could have been an issue caused by the improper oil being ran through it, but even when it was burning the undyed oil it achieved top speed. Could it be an MPEM issue, idk, I’m a newer Seadoo owner and learning on the fly. Any help would be greatly appreciated and if I do come to a conclusion I will post the fix.

 

[switt]

My hunch would be the carbs, specifically the low and high speed screw settings.

 

[Phuck_boi]

I appreciate the response, I just rebuilt the carbs and have them set to factory settings. It ran a little better and I had it on the water yesterday and I think I narrowed down the problem. With the engine compartment open it will scream and hit above 6200rpm, I think it should be higher but wait, and as soon as I shut it it drops by 1000rpm so I believe exhaust gasses are causing a breathing problem. I noticed water coming from the head pipe where it meets the manifold. That could cause the exhaust gasses and the loss of the other 500rpm I’m missing. Next question is, can I use my own gasket with red rtv for this or is it a copper gasket. Taking it apart tomorrow, any advice is appreciated. I circled and put an arrow to where the water was leaking. I didn’t see any smoke, but it’s got to be escaping there if water is.

 

[switt]

Yes, I've used the red rtv and it works fine. In fact, I use it to stop water leak in cyl head jacket. Just don't over do it.

 

[Phuck_boi]

Thanks I’ll let you know how it turns out