Few jetting questions

[werda400ex]

400ex here, piped, k&n with air lid on, and rev box, after putting my new parts on i threw a new plug in and went for a ride, the plug is looking a little lean. I took my carburetor apart to see what it has for a main jet, which is a 148, i couldn't tell what the pilot was. After being warmed up it lacks power from 1/8 to 1/4 throttle, chugging a little which riding, when being stopped and pressing the gas it kind of backfires and chugs from 1/8 to 1/2 throttle. I know you guys are sick of these jetting questions but i don't know where to start. Also where is the air and fuel screw adjustments on this carb?

Thanks in advance

[JOEX]

Originally posted by werda400ex
400ex here, piped, k&n with air lid on, and rev box, after putting my new parts on i threw a new plug in and went for a ride, the plug is looking a little lean. I took my carburetor apart to see what it has for a main jet, which is a 148, i couldn't tell what the pilot was. After being warmed up it lacks power from 1/8 to 1/4 throttle, chugging a little which riding, when being stopped and pressing the gas it kind of backfires and chugs from 1/8 to 1/2 throttle. I know you guys are sick of these jetting questions but i don't know where to start. Also where is the air and fuel screw adjustments on this carb?

Thanks in advance
148 is stock, with those mods you should use a 150, 152 or 155 depending on your local conditions. (Keihin jets)

The mixture screw is on the bottom of front part of the carb, between the bowl and the head and behind the idle adjustment. It is recessed and very difficult to get to while the carb is installed.

[UglyMotha™]

boggin and backfiring are all signs of a lean condition, with those mods your looking at bout a 152 155 like joe said

[werda400ex]

Thanks guys, i'm gonna pick up a few jets and see what happens

[werda400ex]

also, I don't see where you can adjust the needle jet. I've took the whole carb apart and i can't find where you are supposed to change the clip position! I must be retarded

[underpowered]

Originally posted by werda400ex
also, I don't see where you can adjust the needle jet. I've took the whole carb apart and i can't find where you are supposed to change the clip position! I must be retarded

ont eh top of the carb there is a plate held on by three screws. take this plate off, under it is the slide. in the center of the slide there are two small phillips screws. remove these. you should them be able to pull the arm that moves the slide up and turn the carb upside down an the needle will fall out. the clip on on the top portion of the needle. Move it up to lean it out or down to richen it.

[MadMax27]

Mine- piped, with a 1 by 3 inch hole with screen in air lid. 162 Main. 1 size up on pilot, and 2 clips from being the richest on my needle = tan plug.

[werda400ex]

ahhhh okay i see what you mean, i was about to take those screws out of the slide but didn't know what would happen, thanks alot guys!