gotta 03 400ex. lexx slip on w/quiet core, k&n with drilled lid, and 1 down on front sprocket. What jets should i need? and should i have to readjust air and idle screws? if so whats the easiest method?
Also is there much a difference between a drilled air box and running with no lid?

thanks
andy

 

2007 400ex hmf slip on carb spacer 6 1inch air box vents dyno jet 155 main 42 pilot. 2 1/2 to 3 1/2 turns out on air screw 565 above sea level should help ya i may be just a bit rich too. on running no lid theres a difference if you get water and mud in there.id keep my lid

 

where did you get your carb spacer and did you notice any gains? also ive took apart smaller carbs on 125cc engines, should it be about the same thing just bigger. dont wanna get in over my head trying to do it myself. basically drop the bowl and put in new jets then make adjustments? what about setting the needle?

 

stock needles only have 1 groove dyno jets have 5 mine is in the middle.if you dont get dyno jets you wont get a needle.carb spacer ebay not sure if it helped i did every thing at once.you will only have to take the bowl off if you dont get a needle.both jets and needle are easy just take your time.

 

is there any benefit to the adjustable needle. will it be ok to just buy the 2 jets i need should both be changed.

 

MY SET UP FOR YOURS IS JUST A STARTIMG POINT ITS NOT GOING TO BE EXACTLY THAT. DYNO JET NUMBERS ARE DIFFERENT THAN SAY OE FMF MOOSE.THE HOLES IN DYNO JETS ARE DIFFERENT SIZES THAN OTHERS.MEANING DYNO JET 155 MAIN IS DIFFERENT THAN A KEIHN OR MIKUNI 155 MAIN JET. NOT SURE ABOUT THE NEEDLE

 

but i will be ok leaving the carb alone except for changeing jets, correct? meaning leave the stock needle, float etc. im actually waitng on the pipe. im curious if the previous owner had it jetted. it came with the k&n and i noticed it had a slip on, once upon a time. so if i put the pipe on and it runs great, just check spark plug and leave it be if it looks fine?
thanks again
andy

 

1st question yes 2nd yes if plug isnt too black or white.if its too lean you will hear popping upon deacceleration. too fat wont run good

 

<div class="FTQUOTE"><begin quote>Originally posted by: moto134

stock needles only have 1 groove dyno jets have 5 mine is in the middle.if you dont get dyno jets you wont get a needle.carb spacer ebay not sure if it helped i did every thing at once.you will only have to take the bowl off if you dont get a needle.both jets and needle are easy just take your time.</end quote></div>

The 05 and newer stock needle has one notch.The older carbs have 5.

 

All the 400's I have jetted have been 168 to 175 main 40 pilot raise the needle 1 and back the air screw out .5 to 1 turn. This is across 7 400's, all 99 thru 03, with different slipons and opened or drilled air boxes.