lacking power

[snoboardatv40]

i have a 98 banshee that i got in a trade and it ran great for a week. it has fmf pipes and silencers it is bored over not sure how much maybe 20 over and no airbox only a k&n filter. then it started to sputter and it runs but has no power. i took off the head and the pistons and rings appear to be fine and the carbs look fine too. the only thing i noticed was the spark plugs were very dark and had some oil on them after i replaced them even when i only ran it for a few mins. any help greatly appriciated. trying to avoid a huge bill from local shop.

[foodaguard]

try geting plugs agin and make shure they are gaped correct then lean out your gas get good oil and mix 40 or 50 to 1 what mix are you using now?

[Mikeman1]

Is your compression still good?

[snoboardatv40]

it was compression i was getting oil blown back into the carbs rebuild is under way 1.oo over and new weiseco kit installed. thanks for the help