i know another jetting question.......i have a yfz 450.. i put on a CT pipe with a K&N and air box lid off ..the dealer jetted it for me with a 165 main clip on #3, im not sure about the air screw....in 2nd gear mid way through the rpms it boggs down ...it does not do it in first or 3rd or 4th gear just 2nd........i put the air box lid back on and it was even worse and it bogged in 3rd.....i took the lid off and took off the K&N, it got better but still bogged in 2nd gear at a higher rpm......im at a loss here...any info will help thanks.....

 

check your sparkplug & see what color it is i would think a 165 might be small but not sure