Backfiring!

[Fast250EX]

I was ridin my 250EX around last weekend and, it backfires slightly all the time but one time I got done from a big top speed run and as i let off, it backfired loud enough to drown out a shotgun.

I am worried that the thing my be running too lean because i have my baffle taken out and am getting ready to buy a UNI filter. I have wanted to rejet it for a while but never got around to it. I will end up buying the jets with the new filter so what size do you think i should get after the filter.

I have heard of people taking their baffles out and putting on a filter and noticing a power increase. Then they rejetted it and noticed a substantial improvement in power. I just want a little more spice in the powerband and a chance to stop the annoying backfiring.

Thanks for any help.

[cals400ex]

i don't know of the 250's have a fuel screw but check it out. it will be a bronze color screw on the bottom of the bowl. just turn this out a little bit and see if the backfiring goes away. like i said, i don't know if they have a fuel skrew or not.

[cals400ex]

to me the fuel screw looks like number 6 in this pic. the o-rings won't be noticable without taking the screw out though.

http://www.servicehonda.com/hard%20parts/atv/trx250ex%20sportrax%2001-02/trx250ex%20frames%20page.htm

[Fast250EX]

Thanks, I'll go to a look at it. I hope it works cause i hate backfiring.

-F250EX

[ryanh250ex]

Originally posted by Fast250EX
Thanks, I'll go to a look at it. I hope it works cause i hate backfiring.

-F250EX

chances are it wont. i have taken apart my carb and have re-jetted more times than i'd like to admit, and to this day i STILL get popping at high rpms.

bump up your main jet, adjust the e-clip to the next notch down.

[Fast250EX]

Problem solved! I backed it out about half a turn and it no longer backfires except very slightly to where you almost cant hear it after high rpm revs. Thanks a lot, now i can have more fun revving the thing and not have to worry about the annoying firecracker going after after a good rev.;)

[cals400ex]

if your 100% decelerating (not on the gas) it is more than likely your fuel screw/pilot jet. the fuel screw is a fine tune adjustment for the pilot jet. you may notice in the cold months you need to go richer (out on fuel screw or larger pilot jet) due to the cold dense air. you could even try to go out another 1/4 turn if the popping still exists. don't go out too much though. if you go out more than 1 full turn from stock i would just put in a pilot jet one size larger than stock and then start tinkering with the fuel screw again.

glad you got her fixed. :)