Jetting

[jrafter]

After a lot of trial and error i have finshed the jetting on are 250ex.Ive worked on it off and on for the last couple of months not really knowing what i was doing.So i read eveything i could and went back and started from the beginning.

Let me start by stating some of the misstakes i made when i first started.

I add a K&N air filter hoping to get a little more throttle respond like i did with my 400ex...a 250ex carb is not the same as the one on the 400...my first misstake.

after adding the K&N i bumped up the main jet from a 95 to 97.5 keihin jets. i had done this on my 400 and i worked great...... no real change and it was now bogging down mid throttle.

tryed to adjust the fuel screw.....didnt have the right tool so i pulled the carb and adjusted it off the bike 2 1/2 turns put it back together.......still bogging down.

at first i thought i might be hitting the rev limiter but that wasnt it.then i just started changing jetts going bigger,smaller with out really knowing what i was doing or with out any thought as to how i was riding.

first off it almost never see full throttle so changing the main wouldnt have any effect...... since it came with a 42 pilot i thought that was just right because thats what i had to put in the 400....like i said the 250 carb is not like the 400.

i ended up with a 50 pilot jet and i started to see a good respond.I also got a fuel screw from and 04 250ex that i could adjust when it was runing with out any problems and that seemed to help.

IT was running real good but i still had some bogging at mid throttle than i went back to the how-tos on rejetting and there it was......i needed to rays the idle when adjusting my fuel screw get that set and than lower it again.

i ended up with a

50 pilot
needle is stock
97.5 main
fuel screw is 2 /12 turns
K&N

There was a big learning curve for me but it was worth it.
Hope this helps someone else.I know adding just an airfilter isnt much but i have to say on both the 250 and 400 airfilter and the right jetting have add a lot of pep.

also if i had thought about it could have pulled out my fuel screw and cut a grove in it but i went to the dealer and they ordered one for an 04.....getting that set was the bigest pain in the *****

[ryanh250ex]

50 pilot is HUGE. I'm running full exhaust, UNI, no airbox/snorkel/choke and i'm still on the original 38 pilot. I am however having some light off-idle stumbling, so i will have to up it some, but 50 seems to be excessive unless you live at sea level (i am at 150 ft elevation) and it is extremely cold.

[jrafter]

you might might be right.....yesturday was the first time i had a chance to ride it all day out on a lot of trails.

it was running rich.......but it ran great.

im still in the learning curve.....im going to try a 45 and see how that works.

I should have added that im 99% done working on it....but

[ryanh250ex]

Originally posted by jrafter
you might might be right.....yesturday was the first time i had a chance to ride it all day out on a lot of trails.

it was running rich.......but it ran great.

im still in the learning curve.....im going to try a 45 and see how that works.

I should have added that im 99% done working on it....but

try this:

42 or 45 pilot
e-clip one notch below factory
fuel screw turned out some.

[jrafter]

im going to dont just today......i finally collected all the jets that i needed.

[jrafter]

Originally posted by ryanh250ex
try this:

42 or 45 pilot
e-clip one notch below factory
fuel screw turned out some.

i kinda feel dump posting how i rejetting and and everything was great and here im am still adjusting.

i took your advice and went back to a 45 pilot.

than it seemed to be running lean but i did see water in the air box that seem to of come in throught rubber boot for the snorkel.

air leak ...so i sealed up the boots for both the snorkel and the carb and the ideal drop off adjusted fuel srcew and it seem to run a lot better offer the whole throttle range.

[ryanh250ex]

Originally posted by jrafter
i kinda feel dump posting how i rejetting and and everything was great and here im am still adjusting.

i took your advice and went back to a 45 pilot.

than it seemed to be running lean but i did see water in the air box that seem to of come in throught rubber boot for the snorkel.

air leak ...so i sealed up the boots for both the snorkel and the carb and the ideal drop off adjusted fuel srcew and it seem to run a lot better offer the whole throttle range.

air leaks are common if you are fiddling around with jetting i.e. removing/reinstalling the carb constantly.

i'd drop the e-clip one notch if you find that your quad is cutting out when you are at low rpms and crack the throttle.

[jrafter]

Originally posted by ryanh250ex
air leaks are common if you are fiddling around with jetting i.e. removing/reinstalling the carb constantly.

i'd drop the e-clip one notch if you find that your quad is cutting out when you are at low rpms and crack the throttle.

Changing the needle is the only thing i havent done......im not sure how to take it about......

[ryanh250ex]

Originally posted by jrafter
Changing the needle is the only thing i havent done......im not sure how to take it about......

pretty simple stuff.

1) remove throttle cable from top of carb

compress spring (kind of hard) so you can push the slide (cylinder-shaped shaft) upwards so you can remove the throttle cable from the slide

from there i think you pull the plastic collar holding the jet needle in place

you want to move the e-clip (it's shaped like an e and is attached to the jet needle hence the name) lower onto the needle.

removing and reinstalling that stupid collar is the biggest PITA ever, ask me how i know....

hope i've helped
-Ryan

[jrafter]

Originally posted by ryanh250ex
pretty simple stuff.

1) remove throttle cable from top of carb

compress spring (kind of hard) so you can push the slide (cylinder-shaped shaft) upwards so you can remove the throttle cable from the slide

from there i think you pull the plastic collar holding the jet needle in place

you want to move the e-clip (it's shaped like an e and is attached to the jet needle hence the name) lower onto the needle.

removing and reinstalling that stupid collar is the biggest PITA ever, ask me how i know....

hope i've helped
-Ryan

Thanks im back to work now for the next 4 days and i will try it when i get off wednesday.