jetting question

[monson]

i know there are tons of threads on re-jetting but i couldnt find one with what i needed. i just put an hmf slip on, on my 400 and need to rejet. it was backfiring a good bit after i installed it too. my elevation is 41 ft. if anyone could let me know on a good starting point that would be great.

[400exrider707]

filter? lid or no lid? other mods?

[monson]

no. no other mods at the moment

[krt400ex]

backfiring on decel is a lean condition. go up on ur pilot. like a 40 or 42. then go to like a 152 amin. that ahould get u close. u might be a little rich because of ur elevation though. so u will need to play around and see, but definatly need to go richer

[monson]

thanks. are you sayin change the pilot and the main or try the pilot first then change the main if its still not correct?

[nightmare311]

i would do both and also take off the air box lid

[krt400ex]

Originally posted by monson
thanks. are you sayin change the pilot and the main or try the pilot first then change the main if its still not correct?


do both. u said that u didn't jet it at all right?? then u need to change both jets. main = 152 and pilot = 40, or 42. that should be ur starting point. if u plan on shelving the airbox lid, then i would do a 42 pilot and a 155 main. i would still use the oem jets. they r easiest to adjust, because u already know what ur base was...