2004 Yamaha 4 Stroke bogging

[fpelton]

I bought a 2004 Yamaha 40-HP four-stroke yesterday and ran it for the first time today. It was winterized prior to the sale. It runs great at a low idle and can accelerate to high RPM under no load. When in the water and I throttle up, the engine bogs down and cuts out. If I nudge it up slowly, eventually I can get [the boat] on aplan and run like heck. If I power down and try to power up quickly, it bogs down or completely stalls out.

The carbs were cleaned at the start of the summer and water separater added.

[boats.net]

That is normally a fuel problem, probably dirty carbs. Does the gas look and swell fresh?

[fpelton]

I have checked fuel flow, compression and spark and all seem good.

I've alreading drained the carbs and started with fresh fuel, so I'm sure that is not an issue either. Should I try removing the needles and seats to clean out before yanking the carb completely off? Should I try running some Ring Free or another product through it first? If I take the carb apart to clean it out, do I need a new carb kit? Carb was just rebuilt in July.

Thanks for your help.