should the E-Clip setting on the mid-range needle effect the idle. on ours the idle is good on the leanest setting. but stills backfiring. only can get it to 1/4 throttle. does the mixure setting needle effect the idle or all the throttle.

 

What ATV are you working on?

Generally, the different fuel circuits will overlap eachother. Idle is mostly the idle mixture screw and partially the pilot jet. As you advance the throttle and RPM starts to build, the pilot jet and jet needle will come into play while the idle mixture screw will have little or no influence. As you continue to build revs under load, the jet needle and slide will have the most influence while the main jet comes into play. At full throttle and higher revs, the main jet is pretty much in total control.

YMMV.

 

check your carb boot between the carb and motor, spray carb clean or something around it and if ur idle increases than you have a vacuum leak and need to replace that boot.

 

more info on the bike would be helpful.

 

Its a 425 magnum. New diaphram, main jet, midrange needle. Mixture screw doesn't seem to be having affect on idle quality, have tried it thru range of leanest to richest. Changing Eclip to leanest setting provides best idle and restart. Idle circuit plugged?. Pilot valve is clear. Carb has been taken out and cleaned. Cannot find the internal filter in carb, I beleive it's on the pilot circuit? Is it possible to be rich in idle mixture, but lean on midrange? Backfiring thru carb at midrange. Thanks for any ideas you might have.-- Forgot to mention, boots have been checked.

 

<div class="FTQUOTE"><begin quote>Originally posted by: Snortwheeze

Its a 425 magnum. New diaphram, main jet, midrange needle. Mixture screw doesn't seem to be having affect on idle quality, have tried it thru range of leanest to richest. Changing Eclip to leanest setting provides best idle and restart. Idle circuit plugged?. Pilot valve is clear. Carb has been taken out and cleaned. Cannot find the internal filter in carb, I beleive it's on the pilot circuit? Is it possible to be rich in idle mixture, but lean on midrange? Backfiring thru carb at midrange. Thanks for any ideas you might have.-- Forgot to mention, boots have been checked.</end quote></div>

If the mixture screw doesnt have any effect, then i would say the slide isnt closing all the way. Check for correct amount of slop in the throttle cable, or incorrect routing of the throttle cable.
Yes each range can be indepentantly rich or lean.