RPM loss at max speed

[Crayola_Dan]

Hey been a while, I've been using the boat with a smile on my face when my right engine started acting funny. At semi-max or max speed it would rev till 6000 rpm then drop to 5000 raise till 6 then drop to 5 again, leaving me to use the engine less then 5000 rpm to avoid this.
What I don't understand is it happens momentarily, I asked a mechanic and he didn't understand or really didn't care, so I'm asking you guys for help thanks.

 

[seadoosnipe]

More info....

Thats not a whole lot of info to work with but I can give you a few things to look into, then respond.

Compression? Have you done a compression test lately? If so, what were the results on the motor?

Plugs? What did the plugs look like? Pulling them now won't do you any good. You need to inspect them at the point your having the problem. What you'll need to do is run at the speed where you have the problem. Run it for about 10 minutes then pull the lanyard. Let the boat coast to a stop then pull the throttles to minimum, then into neutral. Pull the plugs and see if one of them shows signs that it's running rich or lean. This will isolate which cylinder you have the problem with.

If you don't see a real change in the plugs, then you might be looking at a weakend ignition coil. The coil will first shows signs it's going out, at the higher rpm range, where resistance matters most.

Carbs? There is a better possiblity that it's carb related, since the rpm range you are referring to is really just coming out of transition from using both the low speed and high speed jets. With it being the winter, looking over the carbs might be the best course of action at this point. For giggles, you can pull the plugs and have a look. But, coming off plane to idle, your only on the low speed jet, so the plugs will probably look o.k....:cheers:

 

[Crayola_Dan]

Hey snipe thanks fro the response.
On wednesday I took her in for a service, where 4 new plugs were installed, carbs were taken apart and cleaned, as for compression mechanic said both engines were doing great. Since I'm located in the caribbeans theres no need to worry bout cold here.

How may I be albe to check the ignition coil? It's the only point which I guess wasn't checked 2 days ago.

 

[seadoosnipe]

Maintenance, questions?...

Hey been a while, I've been using the boat with a smile on my face when my right engine started acting funny. At semi-max or max speed it would rev till 6000 rpm then drop to 5000 raise till 6 then drop to 5 again, leaving me to use the engine less then 5000 rpm to avoid this.
What I don't understand is it happens momentarily, I asked a mechanic and he didn't understand or really didn't care, so I'm asking you guys for help thanks.

I guess the thread from PA must have been before yours. I thought you were up North.

Question?.... Is this the same mechanic who said "didn't understand or really didn't care"? If so, I'd still check this stuff yourself. Sorry, when I asked for your compression, I guess I expected you'd tell me what it was. Do you know? You sound like your leaving everything in the hands of a mechanic. Do you know the guy? Is he trustworthy?

The reason is because its more likely an issue of the carbs in transition than it is a ignition coil. But, I can get the resistance readings for you if you want to test it. But then, you can ask that mechanic to do it, he should know?

Like I said, I'm not trying to come off in the wrong way, it just seems in post #1 you make a statement about not trusting the mechanic, soliciting our advice, then you reply by saying the mechanic said your motors compression and carbs are o.k............. Kinda contradictory.

 

[Crayola_Dan]

Hey snipe, the original macanic which gave it's maintenance is experienced with with outboard engine and inboard engine including pwc, but since we're in holidays his shop is closed. The mechanic which I asked the question to is one located near the ramp area which offers his service ($$$) when someones boat or pwc fails.

I actually like to be hands on and don't leave everything to my mechanic, it's just that 2 days prior at the shop most of what you ask was serviced so just associated ever answer given to your questions.

 

[seadooya]

Pull the airbox off, and have wife feather the throttle, while you are looking down the throat of the carb, inspecting the brass fitting to be shooting/squirting gas. If not, your "mechanic" did nothing to yuor carbs.

Your misfortune sounds entirely to a fuel related problem. If at the most case, unplug the "RED WIRE" at the rectifier, then try boat again. If all good, replace your rectifier....part #8

http://partsfinder.onlinemicrofiche.com/seadooforums/Seadoo_oem/Seadoo_JB.asp?Type=13&A=27&B=29

 

[Chester]

It sounds like you have a lean condition. To confirm this, slowly pull on the choke to see if it gets better.

Chester