check valve or accel pump???

[michigan rider]

I have a bad hesitation(stalls sometimes) when going from idle to wot. But if just above idle to wot, no problem. Thought it was a jetting issue but went richer and leaner with the main and the needle, neither affected it. Then went to the air/fuel screw all the way in, 2 1/2 out, all the way out still doing it.

so could it be something else like the check valve or accel pump?

[nosliw]

-what quad do you have
-what mods do you have

[michigan rider]

2002 400ex
k/n and big gun slip on

[michigan rider]

anyone?

[Duncan313]

This seems to be a very common problem with FCR carbs. If it runs good except for the bog, leave the main jet and needle as is. Work with the pilot jet and the air screw. My YFZ had similar problems but it only did it when it was in nuetral, not really while I was riding. I did adjust the accel pump but I ended up with it back at the stock setting. The pilot jet solved it for me.

[michigan rider]

it is not a FCR carb, just a plain stock one

[bradley300]

its probably a rich pilot, sputtering from getting too much feul

[michigan rider]

it only has a 42 pilot

[maxxemracing]

i have the same problem and still cannot figure it out gahh!! plus our honda shop is filled with idiots

[Flynbryan19]

A bog from stabing the throttle quickly is a lean condition. Changing the pilot screw position my not be enough. Go to the next pilot jet and see if your condition improves.

[cals400ex]

what jetting are you running now? keihin or dynojets? air box lid modified or stock? what elevation are you at?

[maxxemracing]

MY JETTING IS PERFECT!!! its not to lean it ran fine untill i took the carb off i know that its the accel pump i am 200% sureof it i jus want to know how go around to fixing it

dont be a jerk to thoes you want help from.

[maxxemracing]

sorry i have jus been asked that so many times its not funny and i know what is wrong i jus need to know how it fix it and i was getting agravated becuase it has stumped me for a month now

[cals400ex]

i highly doubt your jetting is "perfect."

well if you know its your accelerator pump just take it apart and clean it/inspect it. pretty simple process....

it is the circular piece on the very bottom of the carb. i am thinking there are 2 or 3 screws holding the bottom on. be very careful, they strip easily.

[maxxemracing]

well its not perfect but it is freakishly close to being right on they dont make a 170.25 jet yet lol i have cleand it a few times now i guess i havent cleand it out good yet