need some help i took my baffle out and cut 2 holes in top of my airbox lid on my 450 and now it seems to back fire on declerations what do i need to do move needle or change main jet? all info will be helpful thanks.

 

Running lean, Need to re-jet. What elevation are you at?

 

i believe 1600

 

I would try a 165 main jet, 3rd clip position on the YZ needle, stock pilot jet, 2 1/4 to 2 1/2 turns on the air mix screw.

165 main jet $5.00
YZ Needle $13.00

 

stock needle on 5th clip ,165 main with a 45 pilot, air screw 2 1/4 turns out. that should get you close.

 

That will work too.

 

thanks for the help ill try that