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View Full Version : Need help! Jetting woes. 400EX


DGA
08-19-2005, 11:24 PM
I've searched and searched and searched.

I have a 2001 400EX it is stock except for a uni filter and full Yoshi rs3 exhaust with airbox lid off.

I live at 1000ft alt. it is approx 80-90 degrees and 85% humidity.

Im running a 152 main, 42 pilot jet, needle 3rd clip position from the top and 1.5 turns out on the fuel screw.

In midrange the bike pops on decelleration and spits some flames occasionally. Bottom end seems decent. If i go to 1.75 or 2 turns out on the fuel screw it seems to be too rich and hard to start. It seems like maybe my needle clip position is too rich mayber? I dunno. What was the stock position? Someone help please.

Also I removed the choke.
cals400ex
08-20-2005, 01:13 AM
if you run keihin jets, this is what i would do:

160 keihin mainjet
needle clip in the 4th position from the top (3rd is stock)
42 pilot jet
2.2.5-2.5 turns out from lightly seated on the fuel screw (with the 42 pilot jet in place)
DGA
08-20-2005, 07:56 PM
I did as per your instructions.

160 main
4th clip position from top on needle.
42 pilot
2 1/4 turns out from lightly seated in fuel screw

Mid to top has never pulled like that. Ran like a raped ape however, i get flames and backfiring on low speed decelleration. It is prone to popping and stalling on startup a lot now. Sometimes it almost wears the battery down starting it. Everything else is great.

For the record i am running a new DPR9Z instead of the dpr8
could this make a difference?


Originally posted by cals400ex
if you run keihin jets, this is what i would do:

160 keihin mainjet
needle clip in the 4th position from the top (3rd is stock)
42 pilot jet
2.2.5-2.5 turns out from lightly seated on the fuel screw (with the 42 pilot jet in place)
KingKash420
08-21-2005, 08:56 AM
i get popping all the time on my lrd pipe, most bikes with straight through pipes do that, the flames are not a problem to the bike but more a problem to the enviroment you are riding in..
DGA
08-21-2005, 09:13 PM
anyone else got any ideas.
cals400ex
08-21-2005, 09:44 PM
the dpr9z plug will make it a little harder to start. the bike will still pop a little bit on deceleration with a full pipe. you could try to turn the fuel screw out another 1/4 to 1/2 turn. when starting the bike, try to not hit the throttle lever. just hit the start button until you hear it fire then hit the gas.