if you are using a dual coil on the middle cylinder then the spare high tension lead needs to be mounted to the frame or engine
lets look at the dual coil and 1 and 3, when the coil fires, energy runs down one high tension lead, jumps the gap on one spark plug to generate the gap, flows across the engine, jumps the gap on the second spark plug and then returns to the coil through the second high tension lead thus completing the circuit
that is a very basic laymans description of how the dual coil works
Dyna mini series coils are crap but they are not your issue
