2003 25hp 4 stroke no power at WOT....HELP!!!!!

[Bill Ford]

Hi, new to this forum... I've looked around a bit and didn't see this on here. I have been racking my brain, and a few knuckles, trying to fix my 25hp Bigfoot 4 stroke motor.
It starts fine, idles fine and runs ok, but at wide open throttle, there is no power and it doesn't run very smooth.
I have installed a carb kit w/ springs, needle and gasket. Replaced fuel line, fuel filter and plumb bulb. New plugs. Drained tank and filled with fresh no-ethenol gas with seafoam. Cleaned the entire carb including the jets.
Please help. Is there something I have missed? Thanks for the great forum!

 

[guyjg]

there is no power and it doesn't run very smooth.

Check the compression. Get a spark test board or make one. Test all spark wires together to compare the spark. It should be blue and loudly snapping at least 7/16" gap.

 

[faztbullet]

Check to see if timing is advancing as its controlled by ECM. If you have a overheat or oil sensor bad it will go into a safe mode and not allow WOT operation as it retards timing. The coil on that motor fires both cylinders at same time so check to see if you have a spark boot problem. Lastly does it pop thru intake at WOT ? If so you could have a valve problem.