NO!!!!! If you route battery voltage to the coil you will fry it instantly. You need to find a wire in the loom that is GROUNDED when the switch is OFF and open circuit in all other positions.
There will be a single wire on the engine that disappears under the cowling - this is the magneto cut-off wire. Disconnect this from the rest of the mower. Crank engine - it should start. Ground disconnected wire - engine should stop. This is the wire that goes to the grounding terminal on the ingition switch.
Any other wires coming out of the engine will be to do with the charging system, and the connections will be model specific, but typically one is grounded, another will connect to battery +ve, and there may be others that run stuff like lights, electric blade clutch etc when (and ONLY when) engine is running.
phil_saunders@bigfoot.com
Phil Saunders
June 2008