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how do you jump start a motorbike with a car?

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by bbyboy, Oct 3, 2008.

  1. i did a bit of searching on google and it seems like its similar to car to car jump starting.

    but the part i dont get is, do you turn the car on?

    some say turn the car on. some say dont turn the car on as it can fry the eletrical system in the bike. which is it?

    the tutorials say the bike and car needs to be earthed before jump starting. how do you know if its earth or not?

    why do you connect the last clamp to the metal part of the bike and not battery?

    sorry for the moutain of questions. i dont want to fry my eletricals or cook myself
  2. Hello, I don't have any direct information on jump starting your bike apart from the reason they would tell you to connect the earth clamp to your bike frame is because the whole bike frame is connected to the negative terminal of the battery (typically).

    I would advise to not have the car running when jump starting the bike. All you need to do in theory is to connect the leads correctly, have both vehicles off and crank the bike. Do not reverse the polarity of the leads or you'll blow the 30a fuse (best case) or the regulator rectifier (second best) or cook your electrical wiring loom and dash (worse case)
  3. thanks for the info.

    you mean both engine off but the ignition is still on on the bike?

    the corrent polarities would be (+) to (+) and (-) to (-)?
  4. I think from memory, the reason that you connect the last neg lead to the body work, away from the immediate area of the battery, is to guard against a spark caused explosion of any gasses which may be emmitted from the battery.
    More of a problem with the older style battery where you removed the caps prior to charging/jumping, not so much of a risk with the sealed battery types of today.

    + to +, and - to -, you can't go wrong. Just make sure that the vehicle that you are connecting the last lead to is neg earthed, it would be rare if it wasn't but always pays to check first.

    Another tip, if you end up having to remove the battery, remove the earthed connection from the battery first, that will guard against arcing the spanner between the live frame (and anything connected to the frame) and the opposite polarity, an easy way to fry things.
  5. #5 saba, Oct 3, 2008
    Last edited by a moderator: Jul 13, 2015
  6. Some early bikes, particularly small commuters, had 6 volt battery and electrics. as far as I know all bikes these days have 12 volt electrics. Be cautious if you are jumpering from a truck as larger trucks have 24 volt electrics. I would be cautious about starting the car when it's battery is connected to a small bike. To be safe, don't do it but many larger bikes batteries are almost as big as a small car battery so it probably OK in that situation. Nearly all cars and bikes use the frame and engine as part of negative (earth) circuit. With a lot of plastics and non-metal parts on bikes there are a lot of earth wires still required for things like blinkers and lights. The lead between the 2 negative terminals is connected first, then the positive terminal of the dead battery 3rd to the positive terminal of the good battery is last.
  7. thanks guys. works like a charm

    lol @ that vid