My girlfriends younger brother bought a Honda 400EX a few weeks ago. He put a white bros pipe on it and screwed with the carbs a little bit. He said yesterday he fouled out a plug on the lake so he put a new plug in and ran it and the plug is soaked. He wants me to help him out with it. Can anyone tell me what the recomended carb settings would be for this quad with a White bros. pipe? I would like to have a starting point, I think he was screwing with the air screw and stuff.

please??

 

1) get a shop manual or call a Honda dealer and find stock settings for air/pilot screws and main jet and needle position

2) your gonna need a bigger main jet...stock i beleive is 148...so go to 160 around there

3) I'm not sure if the stock needle has adjustment, but if not get a dyno jet kit and adjust the needle as needed.

4) just do 1 and 2 and you will be good to go..

5) don't screw around with carbs unless you know exactly what your doing...you mess with a carb you f**k up your machine and you get pissed off with it(tell your friend)

 

stock settings:

mainjet: keihin 148

pilot jet (slow jet): keihin 38

needle: keihin B44A

clip position: middle groove; this is the 3rd clip from the top

fuel screw position: 2.25 turns out from lightly seated


try these settings with the air box lid on:

mainjet: keihin 152-155

pilot jet (slow jet): keihin 42

stock needle and stock clip position

fuel screw position: 2-2.5 turns out from lightly seated

good luck

 

The problem is the jetting of the carb did it have a stock muffler before the white bros pipe?