breathing problem

[ccjeepman]

my buddy has a 90 warrior runs tits without air filter on, but if you put filter back on it falls on its face past half throttle. put my filter on his does same thing but if you take it off again its great. so needless to say he been running with out his airfilter any suggestion on wat me need adjusted? it has a high comp domed racing piston, hmf sport exhaust,150 main jet, and airbox lid is cut any suggestions would be great thanks guys. by the way his is on the left of my avatar photo:???:

 

[duneracerweston]

Clean the air filter or put a better filter on it. Or rejet it.

 

[ccjeepman]

Clean the air filter or put a better filter on it. Or rejet it.

when it comes to jetting is it mostly trial and error till u get it where you want it. im new to carbs.

 

[duneracerweston]

Search plug chop, or look in the how to's and look for the thread on carb tuning.