What Causes A Starter Solenoid To Go Bad. A solenoid is a low-amp relay system that bridges the high-amperage electrical connection between the battery and the starter motor when you turn the ignition key to start the mower. If the starter motor is turning but occasionally the engine isnt then it is the starter one-way as 02 suggested.
Several problems can mimic a bad starter solenoid or starter motor. Loose or corroded battery terminalscables. Nothing short of a siezed starter would cause premature solenoid failure - yet you say that the bike started again easily after replacing the solenoid - implying that it was just bad.
When a solenoid is bad may mean the solenoids plunger is either mechanically stuck in a closed position and therefore always making contact which may eventually cause the starter motor to burn its windings.
Issues with the starting circuit. When a solenoid is bad may mean the solenoids plunger is either mechanically stuck in a closed position and therefore always making contact which may eventually cause the starter motor to burn its windings. Check for nicks in the cables. A simple example of faulty wiring is loose or incorrect terminal.
