Sorry, guys, the RED WIRE connect ONLY to the spark coil...ONLY..The black wiere is not normally grounded...Grounding the red will WILL kill the engine,
The black wire exists ONLY to use as a kill wire..Grounding the black wire grounds
the source coil, killing the spark....
Be ssure the top screw on the spark coil is tight, it's the ground for that one...
Try disconnecting all wires except the red source to spark coil wires...Be sure the push connectors are tight...Coil failure on any Zenoah is rare,