Old boss had a rear wheel drive Key push mower he loved, just hated pull starting it. He found an old Cub Cadet starter/generator, removed the pull start housing and mounted an 8"(?) pulley to the flywheel, mounted the starter/gen, added a battery with a few wires, and it started like a champ! The battery in the rear between the tall wheels finally ate the 1/4" aluminum deck out after 10 years. Too much voltage was over charging it, or it was spilling acid since it wasn't a sealed one. Since he owned a machine shop, modifications like these weren't out of the question.
David from jax