1997 Challenger 1800 Twin 787(800) Engines

[normsfirebird]

Heres the problem, Out of the hole wide open 7000 RPM both engines. Baot comes up on plain then drivers engine backs off to 5000 RPM and sounds like its bogging, (loading up). Back off throttle to idel throw throttle foreward to max and still no go above 5000 RPM. Once the prop breaks water or pump cavitates it runs up to 7000 RPM. Once prop hooks up or boat palins out it wont run above 5000 RPM. I first rebuilt carbs then completly replaced Carbs with a different set, cleaned rave valves, and replaced all fuel lines and installed new fuel filters. Still no resolution to this problem. Any and all assistance is apprecieated.

 

[seadoosnipe]

Rave Valves!

It still seems to me that you may have a RAVE valve issue. Look at both red plastic caps and make sure they are tightened all the way down for proper spring tension. Also, not only pull them out and check them for deposits, but look at the internal porting that puts pressure on the diaphragms to allow them to open. These valves open and close by pressure on the cyclinder. You may also check the diaphragm for leaks or if it's bad. You may be able to tell this by just removing the caps. It should be clean under the cap at the spring.....if you see a lot of oil residual, you may have a bad diaphragm.
This information comes for the repair manual I use on my 1997 challenger / 5603. I hope it works.........ps, you can get a manual off ebay for less than 10 bucks..........

There's also the second thought, that if your reving up to 7 grand when there's no torque on the engine, like when you pop out of the water, I'd want to know if the bog is due to the engines compression going down. I haven't looked at my book about this, but I believe compression is suppose to be around 140psi.....you can get a compression gage at your local parts store.

 

[JPX]

If you decide to go after the RAVE valves, here is a useful guide for getting into them. Pretty simple stuff - great confidence builder for future mechanical work if you are new to working on SeaDoos.
http://www.theudells.com/PWC/other/rave/rave.htm

 

[seadoosnipe]

Carb?

I think I'd also check your main jet in one or both of the carbs. When your giving it throttle, the pilot jet gives you the first burst of fuel to accelerate. Once your throttle plate begins to go wide open, the main jet supplys the engine with it's gas. You may look at your carbs on that engine. Reading more about the RAVE valves, I don't think that's your culprit.