I have a 1989 Yamaha ProV 150 that is bogging on take off, and surges above 4500 RPM. So far I have replaced the water pump, poppet valve, spark plugs, fuel, fuel lines, and put in a Yamaha fuel/water separator. The compression was between 120 and 125 on all cylinders, and I have spark on all my plugs. I'm assuming that its a carburetor problem, but I wanted to see if anyone can think of what I might be missing, or has any other suggestions before I take the carburetors apart.