2000 400ex after rebuild problems :(

[wzombie03]

ok so i just did a complete top end rebuild, new piston 406 kit, new rings, and all new valve seals etc. got everything togeather and it cranked right up. so i decided to take it out for a test drive and every time i try to give it some gas it seems to bog out and almost die. i remember before i blew the old piston rings it was doing something simialar. Do i just need to Re-jet the carb and clean it? it only sat for a couple weeks or so during rebuild. and my clutch seems a little stiff than it was before for some reason??????????? thanks for any help!!!!!!!!!!!!

[drew416ex]

What jets are in it? Also, at what throttle position is it doing this?

[wzombie03]

im not sure the jet sizes in it, BUT when i got it it already had a stage 2 hotcam and an exhaust and k&n filter and ran well. it seems to to idle well so im thinking the pilot jet is fine. im not sure the main jet size but it bogs down at maybe 1/4 throttle, any higher it dies. so maybe the needle is messed up??

[drew416ex]

Make sure the boot on the airbox side is all the way on the carb. The only way the needle circuit would be messed up is if the clip came out and the needle dropped or there is trash in the carb. Since it idles we know its not the pilot jet.

[wzombie03]

ok so what do you recomend? check the boot? should i check the needle? ive never done any work on these types of carbs. thanks

[drew416ex]

Yeah check the boot. They dont stay on very well. You can see if the needle dropped by taking that same boot off. Look into the carb and give it throttle and you shoul beable to see the needle moving with the slide. If its not those two things then I say there is trash in it. But like i said, check the boot first.

[wzombie03]

ok well the boot seemed to be on pretty good, and the needle i guess it is , is working when i hit the throttle. so i guess i will take it out and take a better look. any recomendations i should be looking for when i get it out and apart? thanks

[wzombie03]

ok it seems to be running fine at all throttle, but when a load is on it in gear thats when im having probs with it bogging out.....maybe i should check the spark plug, ill let ya know what it looks like

[wzombie03]

ok i just checked the plug and it was way black and burnt. so i guess i am running rich right????? since it is idleing fine should i leave the pilot alone and just get a bigger main jet?

[hypersnyper6947]

This may sound stupid but have you checked the parking break.

[wzombie03]

haha........yup :) i dont have a parking break

[wzombie03]

maybe its not a carb prob but maybe a ignition problem?? CDI?? how do i check this stuff?

[wzombie03]

UPDATE


ok i took the carb apart and cleaned it and adjusted the needle jet to the top setting. it seems to be running alot better except still has a little hesitation and sputtering at low throttle....but once at WOT or close it is running like a champ....wanted to come up in all gears!!!! anyways, can someone suggest any more adjustments i can make to get it to run a little better? im still running rich.......no smoking and no backfiring though so i guess thats a good thing....help anyone???

[drew416ex]

You moved the clip to the top one? Where was the clip? Also, did you find out what main jet you had in it while you had it apart.

[wzombie03]

Originally posted by drew416ex
You moved the clip to the top one? Where was the clip? Also, did you find out what main jet you had in it while you had it apart.

yea it is ACTUALLY RUNNING now, i just got back from a 30min ride so i can get the rings broken in. well it must be running extreamly rich, i noticed some black smoke, and i did a 65mph run with a friend down the hw and i sucked DOWN almost a half tank of gas somehow????????????? so i guess i need a new main jet....can i just take off the cap on the bottom to get the main jet out so i can see what # it is????? thanks

[wzombie03]

Originally posted by drew416ex
You moved the clip to the top one? Where was the clip? Also, did you find out what main jet you had in it while you had it apart.

oopps, sory. the clip was on the 3rd one down. i was trying to lean is up a little, but i guess it was only enough to keep it running. i bet the plug is fried.

[wzombie03]

isint there an ADJUSTMENT screw i can turn to make it more lean also??????

[drew416ex]

yes, but that fine tunes the pilot circuit.

[wzombie03]

Originally posted by drew416ex
yes, but that fine tunes the pilot circuit.

ok well i dont know whats going on then, maybe i just need a bigger needle jet

[drew416ex]

Normally the needle doesnt have to be chainged. Its hard to figure out whats wrong without being there.

[CGriff]

do you run it with the airbox lid on or off? if your plug is black then your running rich and you need a smaller main jet.

[wzombie03]

Originally posted by CGriff
do you run it with the airbox lid on or off? if your plug is black then your running rich and you need a smaller main jet.

the main jet is only for 3/4 throttle to WOT which is fine....the problem is at low throttle...which is the needle jet. i think i will try a smaller main jet and see what happens.

[wzombie03]

bump