If the 1999 Kawasaki Vulcan 800 motorcycle is not starting unless you bypass the starter solenoid by hitting both bolts, there could be a few potential issues to consider:
Faulty Starter Solenoid: The starter solenoid is responsible for engaging the starter motor when you press the ignition button. If the solenoid is faulty, it may not be providing enough power to the starter motor, resulting in the need to bypass it manually. In this case, the solenoid may need to be replaced.
Weak Battery: A weak or discharged battery could cause starting issues. If the battery doesn't have enough power, it may not provide sufficient voltage to engage the starter motor properly. Check the battery's voltage and ensure it is in good condition. If necessary, charge or replace the battery.
Loose Connections: Loose or corroded connections between the battery, starter solenoid, and starter motor can prevent proper electrical flow, resulting in starting difficulties. Inspect the connections and clean or tighten them as needed.
Faulty Starter Motor: If the starter motor itself is defective, it may not engage properly when the ignition button is pressed. In this case, the starter motor might need to be replaced or repaired.
It is recommended to have a qualified motorcycle mechanic inspect and diagnose the specific issue to ensure an accurate and proper repair. They can use specialized tools and expertise to pinpoint the exact cause and offer appropriate solutions.