300ex and jetting

[Brad]

when in gear and i get the revs high as i slowly drop the revs it backfires and i have a 128 main, am i running lean? im not sure they make bigger sizes for a 300ex and if i bought a 400ex carb what would i have to jet it at? please help

[darrell43031]

it sounds a little lean. take your plug out and look at it after you ride it if it's a chocolate color it's good if it's real dark it's to rich. if it's to lite it's lean. and yes they make bigger and smaller jets for a 300

[trueblue450]

Originally posted by Brad
when in gear and i get the revs high as i slowly drop the revs it backfires and i have a 128 main, am i running lean? im not sure they make bigger sizes for a 300ex and if i bought a 400ex carb what would i have to jet it at? please help

Try the fuel air screw.. in or out......