The other Day i replaced the stock filter on my cbr 600 with a K&N filter. When i took the fuel tank off i noticed that the previous owner had put decent sized holes into the top of the air box, i guess to allow more airflow. After i put the new airfilter in, the bike hesitated a little when i first gave it gas.Then I put some tape over the holes in the airbox which made it even worse. Any suggestions???

 

The bike is running lean now with that new airfilter. K&N filters allow more airflow so in turn you need to give the bike more gas. Rejetting is needed or get a stock air filter.

 

How much would it cost to have the carbs re-jetted?

 

No idea, I do all the work myself.

 

You may already have the kit installed and now it needs to be tweaked since you changed the airflow (K&N filter). This was the case with my '97.

However on my '96 I had to buy the kit and have it installed. The DynoJet Stage I kit was $95 and the labor was $240. That's about 4hrs labor.