Problems w/ProV-150 Carbs

[Merlin509]

I'm running a 1988 Yamaha ProV150 and am having trouble with high rpm power. It seems to cut out around 4800 rpm and surge. I've had two dealers look at it and neither was able to fix the problem (though they both charged us for the labor and claim they rebuilt the carbs). I've run a compression test and all cylinders check out fine. I bought a new coil and lake tested it while replacing each of the six coils in order and no change. By pulling the plug wires off one at a time and running on the water, I've determined that the problem is in the bottom two cylinders and most likely the bottom carburetor. I pulled apart the lower carb and found no obvious problem, but I have a question regarding the needle and seat.

At one time, a Yamaha service tech said that there had been some problems with these engines getting debris behind the needle and seat where it couldn't escape and causing the sort of problem I'm having. He said that there is a retrofit kit that allows drilling a hole behind the seat to flush out debris and then plugging it with a screw plug. Does anyone know anything about this? I'd also appreciate any other suggestions.

Thanks in advance!

[jb123]

i have an 89 pro v an i have had to clean the carbs up to 3 tmes to get them right before,altho you would hope your dealer would get them right. I would also run the motor at night looknig for spark leaks,as i had to wrap all my coil leads as they were bleeding out.have you changed out ALL fuel lines,checked pickup tube/screen, and fuel pumps?

[Merlin509]

I haven't changed out the fuel lines or the pickup screen, but I did replace both fuel pumps. What is the reason for changing the fuel lines? Should I be worried about blockage?

[jb123]

ALWAYS ensure you have no air leaks in the lines or junctions,like the older models had the quick disconnect, i always ran them direct,deleting that junction.