Jump Starting a Harley

[China twin 88]

is there any reason not to jump start a Harley and if there is no reason as to why not to, is there precautions that should be taken, such as, disconnecting the  bikes battery before attempting to start the dead bike.

[calgary56]

If it's a dead battery on an EFI model, as far as I know, you can't jump start 'em, .... no power to fuel pump, you'll be pushin' it a LONG time.

[Rags722]

If it's a dead battery on an EFI model, as far as I know, you can't jump start 'em, .... no power to fuel pump, you'll be pushin' it a LONG time.

Don't think he's asking about push/bump starting the bike, but rather jumping it off another vehicle. Guess the real question is could you smoke either the car's or bikes charging system or electronics by using a set of jumpers on the bike.

[calgary56]

Ahh, gotcha

[seattledyna]

Reasonably safe to jump charge for a bit, then disconnect jumpers for a try at starting
Check terminals and grounds of course

[China twin 88]

Actually, the bike in question is a carb model and just wondering bout frying electronics.

[truck]

You'll be OK jump starting as long as the donor battery is not being charged by it's alternator. Motor off.

[FSG]

Your pretty safe jump starting a carb bike, I do it every now and then from either a car, a bike or just a spare battery.

[China twin 88]

thanks for the input....

[Ridetard]

If you have a trickle charger connector, do not use ii for a jump.  You will blow the fuse right away.   Dont ask me how I know,

[beebak]

I have a 2007 Dyna Superglide with EFI. Jump started it with my truck a couple of times with no problems. Bike battery was getting towards the end of it's life cycle and wouldn't crank quite fast enough to start when cold.

[Scooterfish]

I`m with Truck Using any 12 volt battery in or out of a car/truck should be fine. The car should not being running thus getting current from an alternator which has way to much out put,

[Phu Cat]

12 volts is 12 volts no matter whether it comes from the bike's stock battery or a donor battery.  Truck is dead on about not having the donor bike's engine runnin.  And it's best to make the last connection (and the FIRST connection to break) at a ground location somewhere other than the battery.

PC

[texaskatfish]

Good STUFF PC!

motor OFF and ground to a bracket or frame part - "last connection" and first one to remove.......................and THEN go buy a new battery of course!

[CrazyRay]

Just for the record, fwiw, you can push start an EFI bike. I've done it many times.

[f-x-d-w-g]

Yes, you can push start an EFI bike if you have some battery to power the ECM and fuel pump.  If not, and the alternator/regulator work OK, you should still be able to start it unless the battery is shorted.

And there's no reason why the donor vehicle can not be running.  The charging system of the donor is maintaining the battery at a bit over 14 volts which will not harm your system - that's what the bike's charging system does.

Good advice about using a ground away from the battery since a charging battery generates hydrogen and you don't want a spark to ignite an explosion!

And, yes, I've jumped my Dyna from a RUNNING vehicle.  No problems at all.

[hrdtail78]

Truck,

I was taught to have donor vehicle off as you describe.  I was also told not to jump the new batteries of a high CCA jump box.  I was told these sealed batts. have a vent fuse in them.  Too much amps and this will blow.  You know anyhting about this?

[harleyjt]

I've always heard to jump start a bike with the donor vehicle off as well.  Always heard horror stories about frying electronics and alternator stators if the donor is left running, due to the additional amperage available from it.  Most bikes of the day charged at a much lower rate than the cars did and couldn't handle the higher amps.  With the higher charging rates now used on later model Harleys it may not make a difference, but I'm not gonna be the one to try it and find out.
jt

[truck]

Truck,

I was taught to have donor vehicle off as you describe.  I was also told not to jump the new batteries of a high CCA jump box.  I was told these sealed batts. have a vent fuse in them.  Too much amps and this will blow.  You know anyhting about this?

Back when I was working at East Penn Mfg., the vents were about as sophisticated as the umbrella valves in the rocker boxes of the TC88. I don't know if that changed. You may find something by looking in the tech manual.
http://www.dekabatteries.com/assets/base/0139.pdf

[hrdtail78]

Thanks Truck.  I didn't read any smoking gun in the tech specs, but it it does say several times and points out the importance of having the correct voltage.  13.8-14.1. depending on temp. Not amps like I thought.  I have seen cars that put out more voltage than this.  It doesn't say anything about the batt taking an immediate crap.  It shortens the life of the batt.

[China twin 88]

thanks again for the info.. so start the dead bike with the doner bike off and hook the ground, to the frame or batter bracket last  and remove  it first ....right?

[76shuvlinoff]

that's how I read it

good luck

[FSG]

.. so start the dead bike with the doner bike off and hook the ground, to the frame or batter bracket last  and remove  it first ....right?

Correct.  The ground lead last on, first off, then there's nowhere for the positive lead to short to when it's being connected.

[f-x-d-w-g]

Ohm's law versus HTT's rumors.  I guess the rumors have it!   

Bachelor of Science, Electrical Engineering, 1972 University of Missouri, Columbia.

Having the donor vehicle not running won't hurt anything.  Neither will having it running.

[hrdtail78]

Ohm's law versus HTT's rumors.  I guess the rumors have it!   

Bachelor of Science, Electrical Engineering, 1972 University of Missouri, Columbia.

Having the donor vehicle not running won't hurt anything.  Neither will having it running.

Problem with car running is unknown voltage.  I have seen cars that put over 14.5 out in the charging system.  Not rumor.  Fact.  Practical.  Go check three cars on your block and tell me what they put out voltage wise.