I have a question about the performance of my newly refreshed/787 carbs?

[grusnak1001]

I was having some low end issues with one of the carbs, so I cleaned them both and also replaced the diaphragm on one of them. (No holes, it just looked a little wonky-i.e. wavy). This is the only Sea-doo I have ever owned/driven. Before the re-do, The ski would act as if it had a 2 speed transmission with a big "jerk" when the high speed jet would kick in around 4000 rpm. After the re-do, it acts more like a vehicle with a continuous variable transmission with NO "jerk". It will easily rev to 6000 rpm during acceleration until prop slippage is gone before reaching 6500-6700 rpm WOT. My question is: Which senerio is "normal"? If I did something wrong during the re-do, can anybody explain what is was. or is this the normal way a Sea-doo should perform?

 

[mikidymac]

Try cleaning the RAVE valves, they typically open at 4,500 rpm.

 

[grusnak1001]

I appreciate your input, but what could have changed in a week?

 

[mikidymac]

My guess is that it is your carbs. If you didn't replace everything except the springs with all new Genuine Mikuni parts, including needles and seats that is most likely the issue.

 

[grusnak1001]

I appreciate your input mikidymac. Can you take a guess specifically where the issue lies?

 

[mikidymac]

Sounds like the carb isn't transitioning cleanely. Also pull the raves and clean them. Both a re big maintenance items.

 

[grusnak1001]

I don't understand by Both a re big maintenance items. Can you spell it out?

 

[mikidymac]

Sorry typing faster than thinking...
The raves should be taken apart and cleaned and new stem o-rings installed. If they stick they will cause your issues. THey get gunked up with carbona nd 2-stroke oil.

The carbs should be completely be rebuilt with all new Genuine Mikuni parts including new needles and seats. Do not use new springs unless yours are damaged. The carb rebuild thread is a sticky a the top of the 2-stroke page.

 

[grusnak1001]

I may have to do that, however I just read what reed valves do and it says dirty ones cause lack of power which is NOT my situation. If that doesn't do it I may well leave it alone as the power and acceleration is there but I kinda miss the "jump" at 4000 rpm.

 

[mikidymac]

These don't have reed valves.

The RAVE valves give a combination of bottom end then open and increase top-end. So if they are sticking they might not open smoothly and cause the lag, delay in opening and performance.

 

[grusnak1001]

My bad! reed/rave (they sound the same to me) The RAVE valve you're referring to. There are 2 on top of the engine and one down ob the exhaust canister. I'm guessing you're talking about the 2 on top of engine. Right? (forgive me-I am so unmechanical)

 

[mikidymac]

Don't touch the one on the exhaust yet, it isn't a RAVE valve. Just the two in the engine.

 

[grusnak1001]

Don't touch the one on the exhaust yet, it isn't a RAVE valve. Just the two in the engine.

Thank you-BUT just to be clear, there definitely is NO lag. just a smoother transition across the power range.