400EX bogging bad!!!

[wlsmoku]

please help the newb with issue. my neighbor has a 00' 400EX with a white brothers exhaust, K&N filter, and a snorkel. it doesn't run very well in 1st, and the rest of the gears it bogs pretty bad at 3/4 throttle to WOT.

Any suggestions?

does it need different jetting with the mods?


sorry if this is a dumb question, I'm just trying to help a neighbor :)

[2000400EX]

Uummm...yeah, if the carb still has stock jets in it, it'll definately need some larger jets. Not sure what ones though....someone else will be able to help ya out with that.

[wlsmoku]

I found out he had a friend put a 160 in it, and he said it got a little better he thought, but wasn't sure.

what size is stock?

[2000400EX]

Stock is a 148 for the main, 38 for the pilot, and 3rd clip from the top on the needle.

[wlsmoku]

Originally posted by 2000400EX
Stock is a 148 for the main, 38 for the pilot, and 3rd clip from the top on the needle.

excellent - many thanks for the details!!!


if anyone has any suggestions on jettings and needle location, I would greatly appreciate it.

I am located in MO, apx sea level is 1600ft if that matters too much.

[wlsmoku]

few more details from the owner:

it will idle ok for a few min after starting it, and then it starts running crappy, and no matter what throttle position in 1st gear it stays running bad, but in 2nd and on it runs ok up to 3/4 throttle (running horrible after 3/4 though)

[400exrider707]

I would try moving the clip on the needle down one position to richen it a bit, up the pilot size one step to a 40, and possibly drop the main down to like a 155 to lean it a tad. 2 1/2 turns out on the mixture screw should be ok too. These are just ballpark by the way, you will still have to fine tune.

[wlsmoku]

Originally posted by 400exrider707
I would try moving the clip on the needle down one position to richen it a bit, up the pilot size one step to a 40, and possibly drop the main down to like a 155 to lean it a tad. 2 1/2 turns out on the mixture screw should be ok too. These are just ballpark by the way, you will still have to fine tune.

many, many thanks for the newb help guys - I do appreciate it :)

I'll let ya know how it turns out!



one more ?.....is it stamped on the jets what # they are? I just want to be sure I am making a positive change from what is in there currently...

[ocitman]

i have a K&N and a DMC pipe with a 155 main jet and a 15 tooth countershaft sprocket. it runs great with lots of power at lower elevations. at higher elevations it lacks power.
i bought a 150 and 152 main jet and will try it at sand mountain, starting with the 152. Dont want to run it too lean and burn it up.

[wlsmoku]

update:

replaced the main with a 155 (from a 160). the pilot was still stock jet, and the needle clip was stock setting too. The spark plug was BLACK after 2 weeks of minimal running, so I know it was rich as heck. the idle screw was way out of adjustment too, so I reset that as well. cleaned everything I could see, and still not starting. It hasn't started all week he said. I sprayed some carb cleaner in the inlet while trying to crank it,and it fired right up (died quickly though). Any MAIN areas in the carb I need to be looking for gunk now?

it's def carb. gas is getting to the carb for sure, and It is getting into the bowl also. from there I do not know....

[Jonas]

Did you physically take out the pilot jet and clean it?

Explain to me what kind of "snorkel" he has.

Is there any difference if you remove the air box lid and try and start it?

What elevation range and temp. do you ride at again?

[ocitman]

pull the plug and crank it over with a paper towel over the plug hole. is it getting wet with gas?
is the choke on when you are trying to start it?
155 main jet and its running rich? i dont remember if you said you have a pipe and air filter on it.
try going back to a stock 148 jet but if you do have a pipe and air filter on it, i think it will be too lean.

as for the carb-a-tooter, remove it and clean it out really good. blow some air thru the bosses. could have a small piece of sand in there.