I removed the air filter screen on my cr450 Y05 and lost about 1/3 of my overrev. Twin Air told me no jetting was needed. But my friends experienced the same thing. We went from a 168 main to a 170/172 and got our power back and over rev. 172 gave a little bit more over rev over the 170, so most of us are running the 172 here in central CA where the temp is currently 60 degrees. YOU MUST RE-JET RICHER!!!!
