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Common Tread

How to jump start a motorcycle

Dec 10, 2020

The dreaded "click"... When you turn your key on, hit the starter button and hear a big click, or maybe a series of clicks, or even a few slow cranks, and you realize you're not going anywhere fast.

It just so happens that between the time I was assigned to write this article and now, one of my motorcycles and my truck both experienced battery problems. Has Editor Lance been sabotaging my vehicles to remind me to get this done? We may never know.

I have had a lot of vehicles over the years with “no-start” conditions caused by dead batteries, so I will share some of my experiences and advice that will hopefully get your bike going as quickly as possible. 

First, just a reminder that there's a difference between the motorcycle turning over but not starting and the battery being too weak to turn over the engine. This article is about the second scenario. (Also, see our article on how to test a battery if you're not familiar with the procedure.) So let’s talk about a few things that could have led to your bike not starting because of a lack of juice from the battery.

Checking a battery with low voltage.
Your typical "dead but probably jumpable" battery voltage. This reading should be above 12 volts. A completely drained battery may resist coming back to life without a long recharge. Even then, a fully drained and recharged battery might not have much life left in it either way. Photo by Joe Zito.

Situations you can fix with a jump start

In the following scenarios, your bike’s battery is usually still healthy enough to accept and hold a charge, so a jump start will be a quick and easy fix.

  • Did you accidentally leave your parking lamps or an auxiliary device, like a phone charger or GPS, turned on after shutting off the bike? That steady drain can weaken the battery to the point it won't turn over the engine, which takes a lot of power. If you accidentally drained the battery this way, don’t feel too bad about it. It is a common mistake and is easily resolved by a jump start.
  • Has your bike been sitting for more than a few weeks without a trickle charger connected to the battery? This is typically the most common reason riders need a jump. Batteries discharge over time and are naturally weaker as the temperature drops. Combined with cold, thick engine oil, the battery may not have the amount of energy it takes to get that beast fired up.
  • Another issue I see during the colder months is caused by heated riding gear. Heated gear is an awesome way to extend your riding season or even ride year-round. The downside is that it uses a lot of electricity. If your bike’s alternator does not make enough excess electricity to power your heated gear, the draw will discharge the battery while you're riding, especially in city riding with the engine revving at lower speeds. I experienced this with my Triumph Scrambler 900. I could run the heated gear on high while riding on the highway, since the alternator was cranking out a lot of juice at the higher rpm, but when I got off the interstate I had to be sure to turn the heated gear down or off to ensure the battery would be kept fully charged at lower revs. If I failed to do so and turned the bike off, it would not restart.

Situations you can't fix with a jump start

Unfortunately, these situations might not be remedied by jump starting:

  • Batteries have a lifespan. I have found that in an area with all four seasons, like here in the mid-Atlantic region of the United States, motorcycle batteries tend to last a few years, at best. With the extreme temperature range they must endure each year, they will eventually lose their ability to accept and hold a full charge. At this point, a jump start may not work. Even if it does, the bike will likely shut off again as soon as the method of jumping is removed from the dead bike’s battery. A replacement battery is the solution. (Check out our video on how to replace a battery if you're not sure how to do it.)
  • You stopped for gas and now the bike won’t start, or your bike may have just shut off while riding, like my vintage Triumph did last week. In this scenario, chances are your charging system has failed. If your bike is not generating enough electricity to keep the battery charged while you’re riding, your lights, ignition and fuel pump may have used up the last of the juice in your battery, causing the engine to shut down. While you may get the bike fired up again with a jump start, the bike will likely shut down again very soon. Be careful with this situation as you could give up a decent place to break down, like a parking lot, for a much worse one, like the interstate. This situation calls for further investigation. Generally, a failed stator, regulator or broken wire is the cause. My old Triumph’s stator wire rubbed through and grounded on the frame, frying my regulator. Lucas, the prince of darkness, strikes again. I needed to replace my stator and regulator to get the bike recharging its battery again.
  • Modern bikes usually have two safety switches that must be closed before the starter button will crank the engine over. One on the clutch lever and another on the side stand. These are small and somewhat fragile switches. If you are hitting the starter button and getting nothing at all, make sure your side stand is up and your clutch lever is in. If they are and still no cranking is going on, check these switches and the wires going to them. I have saved a few bike trips by bypassing broken safety switches, so you might want to give that a shot before calling the tow truck.

Jump starting a motorcycle battery.
Motorcycle jumper cables can fit in the tight spaces motorcycle batteries usually live. Be careful if you have to use large, automotive jumper cables as it is very easy to accidentally ground them to the frame, which will make sparks and could ignite nearby flammable vapors. Photo by Joe Zito.

How to jump start a motorcycle

OK! Now that we’ve gone over some situations where a jump start will work or will not work, we can finally talk about doing it.

If you are not in a rush, I recommend connecting a charger to your battery until it is topped off. This is technically not a “jump start,” but the slow reenergizing of your battery will ensure it remains as healthy as can be when you are ready to ride.

Using a jump pack or personal power supply to jump start a motorcycle battery.
My Antigravity Micro-Start XP-1 Power Supply has gotten dozens of dead vehicles running again. Photo by Joe Zito.

If you don't have the time or the ability to use a charger, the next best option is a personal power supply or “jump-box.” This is a must-have, in my book. Aside from being able to jump start your bike or car in a pinch, without anyone else’s help, they can also recharge your electronic devices and usually have a built-in flashlight. Turn the device on, connect the red alligator clip to the positive battery terminal and the black one to the negative terminal on your bike and fire away. I have used my personal Antigravity Micro-Start XP-1 Power Supply to start several friends' trucks and dozens of bikes. I also use it to recharge my camping lights, phone and GoPro on motorcycle trips.

Finally, let’s talk jumper cables. This is really no different than jump starting a car. You can jump a motorcycle with another motorcycle or a car. There are differences of opinion about leaving the car or truck running while jumping a motorcycle. I’ve seen it done without any ill effects on the bike, but why risk it when it's not necessary? A large car battery has plenty of energy to fire up a bike within a few seconds, without the need for the engine to be running.

Accessing a motorcycle battery by removing the seat.
If possible, place the ground clamp on the "dead" bike on a chassis ground like this frame hardware. This keeps potential sparks away from flammable vapors. Photo by Joe Zito.

When using jumper cables, just remember the phrase “red to dead.” Start by hooking up the red cable to the positive terminal on your dead bike. Then connect the other end of the red cable to the good battery's positive terminal. Next, connect the black cable to the jumper’s negative terminal and lastly, the other end of the black cable to a bare metal surface on the dead bike. If you can’t locate one or are afraid of scratching things up, hooking the final connection up to the negative terminal on the dead bike is fine. The idea is to keep any sparks away from the battery as the gases that can potentially be released from it are flammable. Reducing the chance of sparking is why jumper cables made for motorcycles have alligator clips that are smaller to fit the small terminals on a motorcycle battery and the confined spaces they live in.

Having a friend help push you to bump start a motorcycle
Having someone give you a push is the next best alternative to a long downhill for bump starting a dead bike. RevZilla photo.

Bonus section: How to bump start your motorcycle

So, your bike won't start and you've confirmed your battery is likely "jumpable," but unfortunately no one is around and you do not have a personal power supply on hand. Time for a bump start. If the battery is too weak to turn the starter but still has enough juice that the lights come on when you turn on the key, you can probably bump start it. On EFI bikes, you can listen to hear if the fuel pump runs when the key is turned on. If your battery is too drained to power the fuel pump, a bump start won't work on a fuel-injected bike.

Bump starting is starting the bike by turning over the engine with the rear wheel instead of the starter motor. Generating some momentum, by pushing your bike or rolling down a hill, will allow you to put that energy through the drivetrain, into the crankshaft, forcing it to draw in some fuel and air, then compress and ignite the mixture in your combustion chamber, resulting in a running bike.

Starting at the top of a hill is the preferred method since pushing a motorcycle with enough speed to fire it up can be tough work. I recommend having your ignition on before you get rolling, but leave it in neutral since this avoids the drag of the clutch plates, helping you gain a little more speed. Once you are rolling at no less than a jogging pace, pull the clutch in, pop the bike into second gear and plop your butt down on the seat as firmly as you can while simultaneously dumping the clutch. The butt plop is essential to prevent the rear wheel from skidding. It gives you a burst of additional traction right when you need it most. You will hopefully hear the bike fire up so you can pull the clutch right back in and rev it a little to keep it from stalling and allow the alternator to begin recharging the battery. If it does not fire up on the first try, it may be worth giving it another shot or two to perfect your timing.

Checking the charge rate of a motorcycle battery while it is running.
Once your bike is running, be sure your charging system is working. Typically, you should see around 14.0 to 14.7 volts. Check your manual to see the specs for your model specifically. Photo by Joe Zito.

Hopefully now you feel a little more prepared for the next time you hit that starter button and hear that dreaded click. As always, feel free to share your "dead bike" stories below and if you need help finding a new battery for your bike or a personal power supply to add to your tool kit, reach out to one of our gear geeks at (877) 792-9455 or shoot an email to cs@revzilla.com.