97 redhead 700 spark issue

[JERSEYJOE]

Trying to helps out a young local lad. 97 SX700. Has 125 compression, basics good, carbs clean, reeds good.

Has only spark to one cylinder. Someone replaced the coils but only 1 cylinder is firing.

CDI Box?

[74Nitro]

More likely stator. CDI's rarely ever fail.

[sideshowBob]

The 97-99 Red Heads spark all three coils at the same time so if only one is sparking check spark plug caps, coil wires, wiring to the coils, and proper coils installed. If all that checks out then its prob rusty flywheel and or defective stator.

[A couple of bucks]

Move good coil to another cylinder and see if the spark follows.

[Maim]

x2 on rusty flywheel. fixed my brothers last year doing the same thing and his was the rust on the flywheel.