What is stock 400EX carb?

[mthomas]

Can someone tell me what the stock Keihin carb on a 400EX is? The manual says it is a QB10A. When I look on Keihin's website they don't list any QB's. Also, which pliot jet is is supposed to have? The 28 MM long one or the 23.5MM long one? My EX currently has the 23.5MM long one. The 28MM jet would stick out of the end of the recess that the pilot jet screws into. Any help would be greatly appreciated. :(

[Rico]

stock carb is a 35.5 mm carb.

Stock pilot jet is 38, don't know about them measurements your talkin about. The jet will have the size stamped on it.

[cals400ex]

when you say pilot jet are you referring to the slow jet or the mixture screw?

with the slow jet, stock is a keihin 38 (21 series).

once you go larger, i think 40 or 42, the slow jets are alittle longer. this is fine and it fits right in (as long as you buy the 21 and NOT the 22 series jets).

[mthomas]

What is the "name" of the stock carb? Is it an FCR?

[mthomas]

I am referring to the slow jet, not the fuel mixture screw. Keihin has a N424-21, N424-22 and N424-26 (or 991031-420 for "VB side draft carb"). The 21 & 22 are the same (they are both 28MM long) except for the location of the threads. I know that the 21 has the correct thread location. I measured the stock #38 slow jet and it is 23.5MM long, which matches a N424-26. The end of the 26 jet is down in the hole, whereas the longer 21 will stick out of the hole as it is 4.5MM longer. Is this OK?

[cals400ex]

here is the part number for the stock carb:

16100-HN1-013 CARBURETOR (QB10A B) 01-04


here is the stock slow jet #:

99103-420-0380 JET, SLOW (#38) 99-04


when you want to change the size of the slow jet, just substitute the size of the slow jet you want in where it says 38 in this part number.

[400exredrider]

no its not a FCR but you need to get a FCR :D