what size sotck jets are in a yfz450 (2006 if it matters) just got an FMF full jet kit and im running just a HMF slip on any suggestiong on what size jets to use? i went riding with out jetting just to see what would happen, and as soon as i let off the gas and pulled to clutch in to slow down the bike would shut off also sometimes the throttle responce stuttered would that be fixed by just a larger piolet jet? any suggestion would help out alot im new to yamaha bikes!

 

Weekend Warrior, i have a HMF Bill Ballance Full exhaust system and friday just tried to instal a GYTR jet kit. Ive been having a horrible time getting the bike in tune with the kit. Everytime you let off the gas the bike will completly shut off, in other words, the bike refuses to idle. But to answer your questing im running in it right now a 160 jet. So i will let you know how that does as soon as i get the bike running. I hope this gives you alittle insight to what you might be getting into, and you might want to consider taking it to a dealer to get done

 

Stock is 158 main 42 pilot #3 clip on needle 2 turns mixture which is normally kinda lean to even start out with. Both of you should try a 168-170 main depending on the elevation, 45 pilot and get the NVCQ yzf dirt bike needle on the 4th position and the fuel air mixture on 2.5 turns.
Hope that helps