26-10-13, 03:57 PM
The ground for the spark plug is the engine which is connected via a cable at the rear right hand side to the battery's negative terminal.
Your reading of 10.5 v sounds a bit low, the positive ends of the coils are connected via two switches and a fuse to the battery so you should be getting a couple of volts more than that assuming the battery is healthy. Exercising the run/stop switch with some contact cleaner might help.
Your reading of 10.5 v sounds a bit low, the positive ends of the coils are connected via two switches and a fuse to the battery so you should be getting a couple of volts more than that assuming the battery is healthy. Exercising the run/stop switch with some contact cleaner might help.