My 88 Bullet has a solenoid switch mounted on the bulkhead in the engine compartment that can tie the Port and Starboard batteries in parallel while starting. Does anyone know how the control side of this swicth was originally wired? I have a wiring diagram for the Bullet, but part of it is cutoff.

P.S. it cannot be wired directly to the engine start switches, as this would tie both switches together through the solenoid, causing both engines to crank at the same time.

My Gun has the Parallel Sol. It closes when The Port or Starboard Start Button is pushed. This allows both batteries to start the engine. Both Engines will not start at the same time as there is another Sol at each starter. That engine starter Sol is the one that applies power to the starter and starts the engine.

Is the solenoid you are referring to the second terminal on the starter solenoid, that is normally unused (in the old days, this contact was used to supply full voltage to the ignition coil while cranking on vehicles equiped with ballast resistors)? If the parallel switch were connected to the small start relay usually mounted on top of the engine, again, cranking one engine would supply power back to the common post of the parallel switch, and the other engine start solenoid would energize and crank.