if I remember correctly there are 2 coils on that bike, 1 coil=2 spark plugs check the other 3 if they spark good not the coil, or anything before coil. would have to be plug wire or boot or even spark plug.
Replaced wires and coil on front. No fix. I read that the drain screws on the bowls must point towards center of the bike.(backwards) or a lean condition will occur.( mine are out) Runs good on choke. With no choke I get a big backfire in the pipe every couple strokes.