I know jetting Q's are beat to death but im stumped

[f4istunna]

Sorry for another jetting question but im stumped on my gf's 400ex.

I think im on the right track as its getting better but still wont idle right all the time and puffs some smoke usually just when cold(going to do rebuild this winter which hopefully cures that)

Motor is stock, only thing ive done is the crf cam chain so far.

when i bought it for her it had alum open airbox, kn filter 155 main 38 pilot, aftermarket needle, fmf slipon (not sure which model) also looks like am rev box.

We do alot of creek crossings, muddy trails etc so i opted to put a stock airbox w/ lid on it and got a new uni foam filter. Also put a new fmf ti slipon on.

I left the 155 main in, put a 40 pilot jet in, and put a stock needle in w/ clip in the middle (3rd down i believe) fuel screw is 2 1/4 turns out. bike runs good everywhere but idle now. Im thinking its the fuel screw that needs adjusted a little more (i played w/ it but didnt seem to make much diff.) Just wanted to see what you guys thought.

It will sorta hiccup sometimes it stalls when it does this sometimes it doesnt. It does pop on decel but it also has a small exhaust leak at the slipon header joint so i think that may be whats causing that. the plug looks decent, its a little on the rich side (darker brown) but id much rather have it ruch than lean;) Seems to idle good other than the hiccup and occasion stall, has good throttle response.

Thanks for any help, ive been messing w/ this for a few weeks now, searching post, trial and error etc running out of pateince lol.

[f4istunna]

forgot to mention im in NE ohio i think its around 900ft. its roughly 40 degrees during the day

[drew416ex]

Not sure. If you get above 3.5 turns out on the mixture, go up a pilot jet, if it is below 1.5, go down a size.

[f4istunna]

thanks, i think im going to bend a flat head or make some kind of tool to adjust it while on the bike before i mess w/ it again. Its a pain taking it off an on for 1/4 turn at a time lol.

Plus id like to be able to keep it running while i adjust so i can hear the idle.


You guys think the 155 main is a bit high now that i put the stock airbox back in w/ lid?

[flauge]

You ever try running it with the 38 back in after going back to the stock box w/ the lid? Thats the first thing I'd try.;)

[drew416ex]

Not to sure about the main. You will just have to run it and see. The lid on will make a difference though. Motion pro makes a tool for the pilot screw. Its a little pricy though.

http://www.motosport.com/offroad/productDetail.php?prodId=214992&nav=&sMMY=

I use a screwdriver that has a flexible shaft like this.

http://www.sears.com/shc/s/p_10153_12605_03362116000P?keyword=screw+driver

Or

http://www.sears.com/shc/s/p_10153_12605_00973286000P?keyword=flexible+screwd river

[f4istunna]

Ya it ran about the same w/ the 38 pilot, i actually just put the 40 in yesterday because of the popping. *thought i was a little lean* then i noticed the exhaust leak so im assuming thats my popping.

thanks for the link on that flex driver i think im going to get one of those it could come in handy for a few things espeically the carb adjust,

Im going to get that and try to adjust the fuel screw w/ it running, if it goes past 3 turns or so ill go back to the 38 and try it again.

Might bump the main down too, but i dont think its off much since it doesnt bogg or anything at full throttle, im pretty sure its a problem in the pilot circuit since just at idle and some at 1/8 throttle, 1/4 up is good. leaning it up a bit might get me some more power though, which i can afford to do since the plug is dark brown color at WOT plug chop.



thanks guys