Hold on, backfiring is pretty normal, a "fart" after shutting it down, but a sled backfiring when you try to start it, that's a serious problem. Is it pulling the rope from you?
Explain a bit more in depth please.
2011 CF8 LE 141 Cutler stage II race gas turbo, powerclaw track, BD-X oil delete, Koso egt, Bparks light weight bushings, BD-X inner wheel kit, BD-X 2 wheel, BD-X anti-stab, BD-X 40" A arms with 19" floats
Wildchild T top post with 4-6" Rox adj riser, protaper bars, cycra handguards, pro design tether.
BR-tech Thrasher hood and venting.
And a throttle that points the RIGHT way, FORWARD!!!!
250++hp...and still quieter than a sled with a can!
2012 proclimb M800 snopro, BDX oil delete, CE 2.5 track, 38" arms, wildchild post mod, pro design tether, and a hot dogger (and of course, a forward throttle...)
PM me if you're looking for lightweight or diamond drive parts, I can get you discount pricing on BDX parts.