When using a K&N air filter,you are suppose to re-jet and go with (Dyno-Jet Stage 3)You will pay about $125.- for the jet kit.you'll get better performance over all outta your bike!.For instance I tryed the same thing using my stock air box.Later switched to 4-single K&N filters and OMG what a change.But since then my 1992 Suzuki 1100 Katana has had a big make over.I've added a 1349 stroker kit & Flat slide carbs with K&N filters.So my 1100 is plus 249.It beats a stock Busa with ease..But not for sale..The bike tops out at 240 with race fuel and and around 225 with regular gas give or take a few..
You need to post more info. Bike model would help. Is it carb-ed? Did you just put on a new oil k&n filter? You do know those filters need to be oiled. Is it in the factory filter box? Pull a plug and tell us what it looks like (oiled or burnt white).