I have the job of rejetting my friends new 450 after we install his new exhaust(Dr D) when it arrives They tell us just to put a 172 main jet in and that will do. Does that sound right?. We have no lid,K+N and outerwares. I would think the GYTR kit with needle etc would be needed.

 

The NCVQ or YZF450 dirtbike needle on 3rd or 4th clip seems to work best for most people. Checkout the other YFZ forums for more detail