Literally, hold the plug, lightly spin the back tire. Get a tingle? It won't really hurt unless you give it a good spin, but you still need to rotate it enough, or just push the bike in pitch black with the plug on the head. lol. I always upgrade my coil and cdi. Never have problems with them, I even weld with them still attached to the bike and hooked up. I keep forgetting to unhook it.