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New 400EX Carb Has Non Adjustable Pilot Screw?

11K views 13 replies 7 participants last post by  TRX2fiveO  
#1 · (Edited)
I had bought a new OEM Keihin carb for my 400EX and I have just noticed that where the pilot screw normally is, there isn't one. Instead it has a brass plug looking thing. I've seen both the original slotted pilot screw and the "D" shaped screw but never this. Anyone have any info on it? How do you adjust it when jetting for air filter and exhaust mods? Does it come out? Can you replace it with a regular pilot screw?
The numbers on the side of the carb are: QB 11ABLEF

The Honda part # for this carb is: 16100-HN1-A42

I've looked at an exploded parts view of the carb on a few different sites such as RockyMountainATV.com, etc. and it still shows the carb as having a regular adjustable pilot screw. I'm baffled and confused with this carb. What is everyones thoughts on this?
 
#4 ·
Ya, I finally got to messing with it cause I couldn't leave well enough alone and managed to pull the plug out reveiling the pilot screw. Looks like I gotta go get a "D" shaped tool now. LOL. :D
 
#6 ·
i think i have this issue as well just picked up a brand new oem carb to rejet since mine had the slow jet broken off in side can any one else confirm this mine had what looks like a brass plug that has been drilled so you can't get it out without usen a reverse dill bit and i,m not sure wether this is the whole air/fuel screw or just a plug covering it...need help :(
 
#8 ·
I hate those plugs, and if you guys get carbs with those just get rid of those plugs, ATVs dont have emissions LOL.
 
#9 ·
yeah we got her all squared away lol the plug is very deceiving compaired to the original flat head screw this one has the d shapped screw
 
#10 ·
Post up a picture of it.
 
#13 ·
Huh, wonder then why when I went to the quad shop in town, the lady showed me some jets for a 400ex, and they were different, and I told her it was a 02 400ex carb on a 300ex bike.

The one's she showed me where pretty much like mine, but longer on the top part.

42-45 slow jets to up my current 40.