I have a 2007 yz450f and I’m running very hot, I have a ton of backfire, and hanging idle. For those who are unaware hanging idle is when your idle in neutral or resting is typically good (guestimation of 1000-1500rpm) but after revving the bike or riding it won’t go down to the normal idle for a few seconds, instead the idle will “hang” open at what I’m guessing is roughly 3000-4000rpm. After a bunch of reading I understand this is likely due to it running lean, a bad header gasket, or the hot start plunger hanging open. I’ve inspected my hot start plunger and it’s not sticking and I put a little slack on it so it’s not under tension. Next I am looking to solve it running lean assuming that is the problem. The previous owner actually mentioned that the bike ran lean for a while. I would assume a good spot to start to fix this problem would be my pilot screw. However where the pilot screw should be it is not. I can only find my idol screw. If someone could tell me where on my carb it is on this bike because I’m somehow missing it I would appreciate it. Otherwise does this bike only have an idle screw?
I would like to add it’s not overheating to the point of puking out coolant. It is just getting very hot and then running very rowdy. I would describe it as being extremely snappy and responsive. Kind of like how a bike runs best right before it blows up..