Stupid Queston but need a answer please

[Kidfunk3]

I have a stupid queston but what is the purpose of jetting is it for higher alltitudes or does it increase performence

[J.D.]

Jetting makes it run at the correct air/fuel mixture. Jetted to rich, your engine will bog, running lean makes the engine run hot and risk burning a hole in the piston. If your getting right you should have quick throttle response and the engine will run like a champ!(Providing you have a good top end)