Rhino, did you put the choke springs out of a '94 KLR 650 in your carbs? That's the ones I put in mine and it has completely cured any choke problems. Also, I had the 142/145 jets in my 650 with the muffler modded and the airbox modded and a Unifilter. I was also getting backfiring. I went to 145/148 jets and it has reduced my backfiring dramatically. I still get a small one now and again, but it keeps the bears away[img]i/expressions/face-icon-small-happy.gif[/img] With a little tweaking, I'll get it to where it's not blasting anymore.