Jetting a 250EX

[jrafter]

Ok i have read all the threads i could find but i still have Qs

First heres whats in it now

42 pilot
97.5 main......stock was a 95
needles at stock setting
k&n filter



stalls when i stab the throttle....do i need a bigger pilot jet?

at about 3/4 throttle it starts to miss...do i need a bigger main jet..

im asking because from what i read the 42 pilot should be about right.

im going to get some bigger main jets and play with it.

also im running a standard plug DPR8EA-9

over the winter i was running a DPR7EA-9 because it was fouling plugs and it ran better with a hotter plug


Thanks

[jrafter]

im wondering if the K&N is to much air for this motor.

could it be that it is getting to much air and no amount of jetting will fix it.

[300exOH]

What is the stock pilot on the 250ex? A 42 pilot sounds a bit large for it. Either way it sounds like you are rich on the pilot circuit but I could be wrong. Have you tried adjusting the air/fuel screw? I haven't messed with the jetting yet on my wifes 250 and it is fine even with a UNI filter. It sounds like you could use a larger main jet though.

[jrafter]

it came with the 42 pilot from the dealer but i think they also use a 38.....depends on time of year sold.

i have tried
95
97.5
102

is the air\fuel screw on the rightside of the carb...i can nly see 2 screws and one looks like a drain for the blow.

i turned the one screw in and the idle gets faster

turn it out and it dies

i have it at 2 1/2 turns and it runs good

i should say with the 97.5 in it runs good but wot it sputters.

its not a big deal but im tinkering.......LOL

[300exOH]

Originally posted by jrafter
it came with the 42 pilot from the dealer but i think they also use a 38.....depends on time of year sold.

i have tried
95
97.5
102

is the air\fuel screw on the rightside of the carb...i can nly see 2 screws and one looks like a drain for the blow.

i turned the one screw in and the idle gets faster

turn it out and it dies

i have it at 2 1/2 turns and it runs good

i should say with the 97.5 in it runs good but wot it sputters.

its not a big deal but im tinkering.......LOL

Did you try it with the stock pilot and main? When I added the UNI filter on mine I never changed the jetting and it has ran perfectly. Usually the air/fuel screw is a brass screw on the bottom of the carb body(not the bowl) and is almost always a pain to get to. Like I said I haven't had to mess with mine so I'm not real sure. Sorry I can't be more help. It sounds like you are on the right track. Just keep tinkering

[jrafter]

i did try just the k&n with the stock jet 95 and it didnt run bad it just didnt run great.

it was thinking of getting a 38 pilot

try with all the combos

i have to go to work so i will nt get back to it till next week

its going to drive me crazy till than

i need a life....LOL

[300exOH]

Originally posted by jrafter
i did try just the k&n with the stock jet 95 and it didnt run bad it just didnt run great.

it was thinking of getting a 38 pilot

try with all the combos

i have to go to work so i will nt get back to it till next week

its going to drive me crazy till than

i need a life....LOL

I looked it up on planethonda and it says the stock pilot should be a 38. I guess yours could be different depending on the elevation where it was sold. I wouldn't expect great gains out of just a filter unless you make more modifications like removing the airbox lid or adding an exhuast. You may have not increased airflow enough to really need any jetting other than stock.

Anyhow good luck with it.

[jrafter]

yea i didnt think i would gain much just make a little smoother.

i thought i could get better throttle respond.....did think it be a big pain.

my 400ex was so easy........now just a filter on the 400 and jets did make a big diffrents

[300exOH]

Originally posted by jrafter
yea i didnt think i would gain much just make a little smoother.

i thought i could get better throttle respond.....did think it be a big pain.

my 400ex was so easy........now just a filter on the 400 and jets did make a big diffrents

I did notice a VERY slight improvement in throttle response on mine but I think the stock intake is pretty restrictive on the 250ex. The pipe is as well. Removing the lid or a maybe an outerwear lid would make a big difference as long as you don't ride in deep water. You may want to try leaving the jetting where you have it and removing the lid and see what effect it has. If it improves then you are probably too rich. If it gets worse then you need to go up with the jetting.