jetting help, everyone that has a jetted 300 look!

[300EXrider02]

I have been fidling with this carb for too long!:p

I got it now like *****, it back fires, (lean) but also stutters when you relaly punch the throttle, I am running like 1 turn about out on the air screw, 42 pilot, 128 main, 3rd clip down, and it seem to be running to lean and fat at the same time...:huh

hard to explain, but when I turn the idle/air/feul screw down to 1 turn the hesitation and quick stutter when hammering the throttle stops...but also making the machine run to lean, when I turn it to 1 1/2 or more it start to have the stutter after heating up again...

I was thinking of going down to the 4th clip down....or going down on the main jet to like 124 or less and turning the fuel/air screw to one turn or more out


anyone have any sudgestions?
K&N on the intructions said to run 4th clip down w/128 main but that is extremly fat...I am at 500ft sea level

[bradley300]

sounds like one jet is too lean while th other (main i believe) is too rich.

[cals400ex]

whats the stock mainjet size and what mods are you running?

[jerry-89-250R]

i ran a 126 main needle 2nd notch down from the top 40 pilot and screw 2 1/2 turns out, had a UNI full exhaust and holes in airbox, jetting is trial and error, but you have too start somewhere

cal stock is #38 pilot 122main

[300EXrider02]

mine stock was 118 if i am not mistaken...

bradley, thats what i was thinking...

I have open box, K&N w/prefilter...yoshi exhuast with silencer...and 42pilot, no choke, 128 main

now what I did, is pushed it down to the 4th clip down...it made the popping and the leanes go away, but its not running to risc...so I think the needle is fine now, but it still hessitates a lot when you hammer on the throttle, say trying to do a wheelie or something...only in the begining...so i think either i ahve to play with the air/fuel screw a bit more, or go downa size on the main, but the mian is 3/4 thrrotle, and everything is fine in the high rpms...

this is another clue now...
say you just put puting around...like really low rpm, crawling around in 3rd or 4th or 5th...it sputters, and chokes and hessitates...uuuuggghh, not a good sound

I did plug reads though, everything seemed fine...I think the 42pilot is too big, so now i either deal with it or fiddle with the air screw more



wheww!! that was a lot:tired:

[cals400ex]

my 400ex would very slightly studder when i was hardly even hitting the gas when going down a hill. i moved the needle down a notch(clip up one) and this fixed my problem. you would always let your bike idle for a little bit and then look at the spark plug. i am betting your rich on your pilot jet. the main jet should be pretty close. how many turns out on the fuel skrew are you?