A jump start borrows power from another 12 V battery so you can start a bike with a flat battery and get it home or to a workshop. It does not fix the cause. Afterwards, find out why the battery went flat.
Safety
- Never jump a battery that is swollen, cracked, leaking, frozen or hot. It can burst. See Battery is boiling, swollen or leaking.
- Only use another 12 V source. Never 24 V.
- A car battery is much bigger than a motorcycle battery. The old MAVCC course warned that jumping from a car can ruin the motorcycle battery and damage its electrics. If a car is the only source, keep the car engine OFF, so its charging system cannot push high voltage into the bike.
- Never let the two clamps touch each other. Never connect + to −. A reversed connection can destroy the ECU (engine computer), regulator and fuses in a second.
- Batteries give off explosive gas. Make the last connection on the bike frame, away from the battery.
- Lithium starter batteries: follow the battery maker's instructions. Many say not to jump them.
You need
- Jump leads, or a jump pack made for motorcycles. A motorcycle jump pack is the safest choice.
- A donor bike or a car with its engine OFF.
Steps
- Key OFF on both vehicles. Lights and accessories off.
- Check both batteries are 12 V and that you can see which terminal is + and which is −.
- Connect the red clamp to + on the flat battery.
- Connect the other red clamp to + on the donor battery.
- Connect the black clamp to − on the donor battery.
- Connect the last black clamp to clean bare metal on the bike engine or frame, away from the battery and fuel.
- Wait one or two minutes.
- Turn the bike key ON, check neutral, and press the starter in short bursts only. Rest between tries so the starter and leads do not overheat. If your manual gives a cranking time limit, keep to it.
- When the engine runs, remove the clamps in reverse order: black from the bike frame, black from the donor, red from the donor, red from the bike.
- Keep the engine running. Ride with lights on only if needed, and go straight to a place where you can test the battery.
Check your work
- The engine runs smoothly and does not stop when the clamps come off.
- No clamp has melted or sparked heavily.
If it did not fix the problem
- The bike still will not crank with a good donor: the fault is not the battery. See Starter relay clicks but the engine does not turn or Nothing happens when I press the starter button.
- Starts on a jump but the battery is flat again next day: Test and charge a 12 V battery and Test the charging system.
- Many kick start bikes can also be started by kicking, even with a weak battery, on bikes with a magneto ignition. Fuel injected bikes need battery power for the pump and ECU.