If a motorcycle, including a Harley Davidson, won't start after sitting for a while, there could be several potential causes. Here are some common issues and steps you can take to troubleshoot the problem:
Check the battery: A weak or discharged battery is a common cause of starting issues. Ensure the battery is properly charged and has sufficient voltage. You can try jump-starting the motorcycle with the help of another vehicle or using a battery charger.
Fuel-related issues: If the motorcycle has been sitting for an extended period, the fuel in the tank and carburetor (or fuel injection system) may have degraded or evaporated, leading to starting difficulties. Try priming the fuel system by turning the ignition on and off a few times to allow fuel to flow and fill the carburetor or fuel injectors.
Check the fuel quality: Stale or contaminated fuel can cause starting problems. If the fuel has been sitting for a long time, it may have deteriorated. Consider draining the old fuel and replacing it with fresh fuel.
Inspect the spark plugs: Worn or fouled spark plugs can prevent ignition and cause starting issues. Remove the spark plugs and inspect them for signs of wear, fouling, or damage. If necessary, clean or replace the spark plugs.
Verify the ignition system: Check the ignition system components, including the ignition switch, coils, and wiring, for any signs of damage or malfunction. Make sure the connections are secure and clean.
Consider the engine's mechanical condition: Issues such as a stuck or faulty starter motor, clogged air filter, or mechanical problems within the engine can also prevent the motorcycle from starting. If the above steps don't resolve the problem, it might be necessary to consult a professional mechanic for a more in-depth diagnosis.
It's important to note that these troubleshooting steps are general recommendations, and specific Harley Davidson models may have unique characteristics or requirements. Referring to the owner's manual or contacting a Harley Davidson dealership or authorized service center can provide model-specific guidance for troubleshooting and resolving starting issues.