[2001400exjjb]

2001 400ex with aftermarket pipe and one 2" hole in air lid. It's backfiring on high rpm decel so I believe I'm running lean.
Been reading the forums on jetting. Think I'm going to try the 42 pilot and 170 main, right now it has stock pilot and 150 main.
My main question is which screw is the air/ fuel mixture screw to turn out 2-3 1/2 turns. Is this the pilot? Please help !

 

[2001400exjjb]

Haven't messed with a carb in 8 yrs, I think I figured out which screw is air/fuel mixture. The screw on bottom motor side that is exposed when float cover is on. The pilot is set in place in the middle next to main jet. Correct?

 

[SlammedRanger]

The mixture screw is on the engine side of the carb down at the bottom. It is very hard to get to with anything but a motionpro 90° screw driver. It will be flat tip more than likely and be up about half and inch or so in the hole. And dont go anything over 3 turns. Anything more is making zero difference. Your goal is 1 3/4-2 1/4 turns out from lightly seated. So to adjust you want to turn clock wise until it lightly seats. (DONT CRANK IT). After you feel it just touch the seat or tighten up slightly you then start turning it counterclock wise counting turns.

 

[2001400exjjb]

Cool, thanks

 

[SlammedRanger]

No problem! Glad to help!