How to jump start a motorcycle safely, step by step

To jump start a motorcycle, connect a charged 12-volt source (a jump pack or another vehicle's battery) to the dead battery with the right cable order, start the bike, then remove the cables in reverse. The safe sequence is positive to positive first, then negative on the good source, and the final negative clamp on bare metal away from the battery and fuel. Check your owner's manual first, because bikes differ.

How to jump start a motorcycle

Read these steps in full before you begin. They reflect the commonly used method, but your manual comes first.

What you need

• Jumper cables, or better, a compact jump pack made for motorcycles or small batteries
• A 12-volt source, either a jump pack, or a car or another motorcycle with a healthy battery
• Gloves and eye protection if you have them
• Your owner's manual

Before you connect anything

1. Check the voltage system. Most modern motorcycles are 12-volt negative ground. Some old bikes use 6-volt systems or are positive ground, and standard jumping methods do not apply.
2. Turn the ignition off on the dead bike, and turn off accessories.
3. Look at the battery. If it is cracked, swollen, leaking or frozen, do not jump it. A damaged or frozen battery can fail dangerously.
4. Find the terminals. On many bikes the battery sits under the seat or a side cover, and some bikes have separate jump terminals. Your manual shows where.
5. If using a car, park it close enough for the cables to reach but not touching the bike, and turn the car's engine off. This is commonly advised, since a running car's charging system is sized for a much larger electrical system than a motorcycle's, and the bike's manual may say the same.

Connection order

1. Attach one red (positive) clamp to the dead battery's positive terminal.
2. Attach the other red clamp to the donor's positive terminal.
3. Attach one black (negative) clamp to the donor's negative terminal.
4. Attach the last black clamp to a clean, unpainted metal part of the dead bike's frame or engine, away from the battery, fuel and moving parts.

That last connection is on bare metal on purpose. Batteries can release hydrogen gas, and connecting the final clamp away from the battery reduces the chance that a spark happens near it. The recommended sequence is meant to reduce the risk of shorting the good battery or igniting hydrogen. Your owner's manual gives the exact order and connection points for your bike.

Start and disconnect

1. Make sure the clamps are not touching each other or other metal.
2. Start the donor engine only if your manual and the situation call for it. Otherwise, use a jump pack or leave it off.
3. Turn the dead bike's ignition on and try to start. Don't crank for long stretches. Give the starter short tries with rests between.
4. Once the bike starts, remove the clamps in reverse: the black on the frame first, then the black on the donor, then the red on the donor, then the red on the dead battery.
5. Keep the bike running and don't let the clamps touch while you remove them.

Can I jump start a motorcycle from a car?

Often yes, but with caution. Cars have large batteries and alternators, and a motorcycle's wiring and small battery can take damage from too much current or a reversed connection. Safer habits:

• Keep the car off, or follow your manual if it says otherwise.
• Don't let the car and motorcycle bodies touch.
• Check cable polarity twice before closing the last clamp.
• Don't use heavy-duty cables carelessly. Make sure the clamps don't short on fairings or the frame.

A small jump pack is simpler and safer for most riders. Jump packs vary, so choose one rated for motorcycles or small engines and follow its instructions. If a car is your only option and your manual doesn't address it, a shop can advise you.

Which jump source should I use?

Jump source	Pros	Cautions
Motorcycle or small-engine jump pack	Portable, no second vehicle needed, often has reverse-polarity protection	Must be charged; choose one suited to your bike's battery type and follow its instructions
Another motorcycle	Similar 12-volt system and battery size	Confirm both are 12-volt negative ground; keep the donor bike off unless its manual says otherwise
Car or truck battery	Usually easy to find	Keep the car's engine off, don't let the vehicles touch, and watch for clamps shorting on fairings or the frame
Battery charger (not a jump)	Gentlest on the battery and electronics	Takes time; use a charger made for your battery type, especially lithium

Whatever the source, follow your owner's manual and the jump pack or charger maker's instructions.

What are the risks of jump starting?

• Reversed polarity. Connecting positive to negative can melt insulation, short the supplying battery, damage the dead battery and fry electronics on either vehicle.
• Hydrogen and sparks. Batteries can give off flammable hydrogen, so the final connection should be away from the battery.
• Frozen or damaged batteries. A frozen battery should not be jump started, because it can rupture or explode. A physically damaged, low-electrolyte or worn-out battery won't be fixed by a jump either.
• Voltage mismatch. Do not connect 6-volt and 12-volt systems.
• Sensitive electronics. Fuel-injected and ABS-equipped bikes depend on stable voltage. Spikes during connection can cause problems.
• Lithium batteries. These can be sensitive to jump and charging methods, and some have a low-voltage protection mode with its own wake-up procedure. Don't jump or charge one that is swollen or damaged, and follow the battery maker's directions.

What if the motorcycle still won't start after a jump?

A jump only helps if the battery was the problem. Check for:

• A dead or failed battery that can't hold a charge. Our post on why a motorcycle battery keeps dying covers causes, and how long motorcycle batteries last explains typical life.
• Loose or corroded terminals. Clean and tighten them.
• A bad starter relay or solenoid. If you hear clicking, see a motorcycle that clicks but won't start.
• A tripped kill switch or sidestand cutoff. Check the basics in our guide to why a motorcycle won't start.
• Fuel or ignition problems, which a battery boost won't fix.

If the engine cranks strongly but doesn't fire, the problem is probably not the battery.

What if it dies again right after a jump?

Then something is draining the battery or not charging it. Common culprits:

• An old battery that no longer holds a charge
• A charging system fault, such as a bad stator or regulator/rectifier (see bad stator symptoms)
• Parasitic drain from alarms, accessories or a short
• Loose wiring or corroded connections

Don't keep jumping a bike that keeps dying. Have the battery load-tested and the charging system checked. Many parts stores and shops can do a quick test.

Should I recharge the battery after a jump start?

Yes. A jump gets you started, but the bike's charging system is not meant to fully recharge a deeply discharged battery in a short ride. Put it on a charger made for your battery type, and read whether you can ride with a bad motorcycle battery if it keeps going flat. Our guide to how to charge a motorcycle battery explains how.

Can I bump start a motorcycle instead?

Some bikes can be push started: turn the ignition on, put the bike in second gear, pull the clutch, roll it, then release the clutch. This only works on some bikes and conditions, and it can fail on bikes with low voltage, immobilizers or fuel injection that needs battery power. It is also unsafe on slopes or in traffic. Check your manual first.

When to replace the battery

If the battery is several years old, won't hold a charge after a full recharge, shows swelling or leaks, or needs frequent jumps, replace it. See how to replace a motorcycle battery for the process.

When to see a mechanic

See a shop if:

• The bike won't start even with a good jump
• The battery dies repeatedly or the lights dim while riding
• You see a swollen, leaking or damaged battery
• You smell burning, or see melted wiring or terminals
• You are unsure about your bike's electrical system or battery type
• The bike has ABS, a lithium battery or other features that complicate jumping

Shops that handle motorcycle electrical repair can test the battery, starter and charging system. To find one, browse the motorcycle repair shop directory.