This probably isn't the best place to ask but i have a friend that has a 2009 yz 250 dirt bike and he just got a new full system Fmf pipe for it and he asked me if i knew anything about tuning the carb, now i know a little bit about it just because i just put a Hmf pipe on my quad and rejected the carb and tuned it but anyways to the point i was wondering if the tunning for a dirt bike is the same as a quad?
Should he turn the air/fuel mix screw all the way in and then 1.5 turns out and see how it runs and then adjust it from there? Should he have to rejet it or should the stock jets be fine?

Thanks

 

Same way for a dirt bike as an atv. 1 1/2 to 2 turns out for a start plus see how it runs. Shouldn't be any stumble or hesitation,plus always check the plug color. Should be a medium tan color at least. If plug is lighter or white color time to rejet.Some can run okay with stock jets just changing a pipe out,some can't.

 

Quads and dirt bike carbs aren't much different. Seat the air/fuel mixture srcrew and back it off 1.5 turns. Start the motorcycle and see how it runs and adjust the the screw while running the bike. I swapped out my spark plug for a hotter plug due to more fuel.