serious lack of power

[Tomnbon]

I have a 1998 425 magnum polaris big boss 6x6 that starts easy, and idles fine, but if you give it full throttle, it takes off strong but then just falls on it its face like it's starving for gas. Here's what I've done so far.
Changed fuel filter checked the fuel pump, replaced air filter, and spark plug, cleaned and rebuilt the carb, checked valve clearences, cam lobes, cam chain timing, and ignition coil. I also checked the ignition timing but my service manual was not clear on what the rpm was supposed to be so I checked the timimg marks and made sure the flywheel key was in tact. They were both fine. Could the CDI cause this kind of problem, or have I overlooked the obvious as I often do. Any suggestions would be greatly appriciated.

[Bruce!]

Welcome to the board!

[tt425]

Welcome to the forum. Have you checked the ETC(electronic throttle control) on the thumb throttle. It needs to be set between 1/16" and 1/8" gap. This is a safety feature and sometimes gets out of adjustment. Some other things to check would be the diaphram in the top of the carb., vacum lines, gas/airbox vent lines, and dirty air filter.

[4getful2]

I agree with tt.
Check carb. diaphragm for cracks, look at the needle while you're in there-center clip position, then look at vent lines on carb. and fuel tank.
Next check broken motor mounts or malfuntioning clutch