I donít think it would. Kill switch might short out and shut off the engine, but I canít see how it would cause backfiring. Seems like 2 separate issues.
It could also be completely unrelated, like those junk factory fuel petcoks. If you havenít swapped to a raptor660 petcok, I would, just to eliminate it causing a problem. Start with that and the usual suspects: dirty carb, dirty air filter, replace spark plug, etc. After youíre sure you have good spark and clean/adequate fuel, then start looking at electrical, like CDI and stator connectors.
94mm bbk, +4 stroker, Hot Cams, Vertex piston, FMF Power Bomb header and Power Core can, KW black diamond valves/dual springs, FCR39, K&N, Elka long-travel LT fronts and rear, Houser +3, +3/4 LT A-arms, American Star pro xs chromoly tie rods, Dyna non-programable, Tusk +3 axle.