Your sportster has a good battery voltage regulator and is charging once you get it running but unless jump start from vehicle only clicks What do do?

1. Check the battery terminals-Ensure the battery terminals are clean and properly connected. Corrosion or loose connections can prevent the battery from receiving power. Clean the terminals using a wire brush and baking soda solution if necessary, and ensure they are secure.

2. Inspect the starter-Attempt to start the motorcycle without pulling in the clutch lever to bypass the starter safety switch. If it starts, the clutch safety switch or wiring may be faulty and need repair.

3. Check the ignition system-Ensure the spark plugs, spark plug wires, and ignition module or coil are in good condition and properly connected. Replace any faulty components.

4. Examine the charging system-Test the output of the alternator or generator using a voltmeter set to AC voltage. It should produce around 12-14 volts while the engine is running.

5. Perform a load test-Use a battery load tester to check if the battery is holding a charge under load. A faulty battery may require replacement.

6. Check wiring connections-Inspect all wiring connections related to the battery, starter, and ignition system for any loose or damaged wires. Repair any faulty connections.

If none of the above resolve the issue, you may need to take the motorcycle to a qualified repair technician for further diagnosis. They can perform additional tests and repairs to identify and fix the underlying cause of the problem.