Re: 89 Force 125 positive cable?
The battery positive cable connects to the opposite side of the starter solenoid from the red wire to the starter motor. There should also be a smaller red wire or red with white stripe connecting to the battery side and the red terminal on the terminal strip near the starter motor through the circuit breaker below the terminal strip. This supplies power to the ignition switch, choke, and solenoid. Without this wire, or if the breaker is "popped" nothing will happen.
The two small terminals on the solenoid should have one yellow wire connected to one (Neutral interlock) and a black ground connected to the other small terminal. If all other wires are correct, be certain the neutral interlock switch and wires are connected and functioning. The neutral interlock is a brown micro switch located below the carbs. It has a white button that must be depressed by the shift linkage to allow the starter solenoid to be energised.
There! See if that helps.