Engine stumbles at full throttle

[prey2none]

When i ride my KFX450 in low to mid throttle range it runs fine. starts quick and has lots of torque. I get no Fuel Inj trouble codes or light. I run the HMF slip on with optimizer. All of the sudden If I go full throttle it stumbles like it is low on fuel. the pump is running, The valve clearance is good, the plug is light brown. What could be causing this?

[kfxmonster]

QUOTE (prey2none @ Jul 25 2009, 12:54 PM)

When i ride my KFX450 in low to mid throttle range it runs fine. starts quick and has lots of torque. I get no Fuel Inj trouble codes or light. I run the HMF slip on with optimizer. All of the sudden If I go full throttle it stumbles like it is low on fuel. the pump is running, The valve clearance is good, the plug is light brown. What could be causing this?

is there any water getting in the intake or there could be somthing loose on the header or exhaust somewhere,these r the problems i had with my bike,good luck with fixing it

[skidoo]

do you do alot of wheelies cause i do with mine an my buddie was riding it doing the odd one an i was riding his suki 450 bike an it back fired so bad i couldnt see the quads behind so an i ended up driving it home an some time after 1/2 to 3/4 trottle ud punch it wide opean it would just go blaw an not realy go anywhere so i toke it to the dealer an they told me theres a breather in the crankcase that fills full of oil if you do alot of wheelies an puts it back in the throttle body which makes it do that so they said theres a drain some place. i donno where yet cause its not done getting fixed from the other problem which is not starting right it always drains the battarie or seems to after couple days of riding an just clicks an they cant seem to fix it so i need help with that to.