701 superjet wont rev all the way

[BBYamaha]

It pulls me out of the water fine but runs like a dog on the top end, feels like I have lost 1000-1500 rpm. It has ran perfect since the rebuild (about 5-6 tanks of gas) but the last trip out I went through a lenghthy no wake 1-2 miles with min throttle acceleration just short burst enough to piss off the locals. It ran good for about 4-5 minutes after I got out of no wake then i noticed i was losing some of my high end, then it gradually got worst and started cutting back. I got off let it sit for 10-15 minutes got on it ran good for a few then cut back again, then i let a friend on it and it ran better for him but I dont think full power. I idled back through the no wake till an exhaust coupling let loose and had to be towed the rest of the way. Put a new clamp on it and and new set of plugs and it acted the same, I prolly ran it about 5-8 mintues before stopping and loading the ski back up, compression is 162~ on both cylinders and the plugs look pretty good (not like the motor is on its way out).

I drained the tank thinking bad gas but there was no water in the bottom, took carb apart tonight but its clean on the inside, I am kinda at a loss, kinda leaning toward the waterbox being stopped up but not sure. Anythoughts suggestions.

will pull waterbox tomorrow...

 

[Crab]

Bet you need to cut the wires back, I had that same thing before getting MSD boots and retainers. Or exhaust in the engine bay.

 

[BBYamaha]

I just replaced Coil pack with a brand new one when i rebuilt motor.....

Pulled waterbox, I can hear water slooshing around but that doesnt mean much, is there anyway for these to get clogged like the supertraps?

 

[tipafew]

ya, I was thinking exhaust in the engine compt. Make sure you don't have any leaks.
I haven't heard of water boxes getting clogged.

You say it "cuts back".....do you still have the stock temp sensor on the head?

 

[BBYamaha]

I do have the temp sensor still hooked up, my buddy had mentioned it but i had forgot about it. How do you test it to see if its bad, I felt the motor and its running luke warm, not much heat to the touch and both cylinders are the same temp.

 

[BBYamaha]

Burned out the waterbox and it runs like a champ now... Poured about a cup of gas into it, lit it on fire let it burn for a few then took compressor and ran air through it, lesson learned stand back a little and gradually get closer pointing the air at the waterbox will creat a torch like effect. I burned mine till the purple smoke stop coming out about 10 minutes