from what i know of bikes - jumping from a car can fry your starter solenoid and possibly your whole electrical system - since it's not the VOLTS that matter, but the amperage.
but - maybe things have changed severly since my 1980 kz650...which is very, very very very likely....
SO - consider yourself lucky if you charge or jump from a car and can ride away.
also considering why they make motorcycle specific chargers and jumpers...otherwise, who would bother?
taken from the website articlebase.com
If the battery won't start or seems dull, you may only need to recharge it. Always check the voltage of your motorcycle battery before recharging and never charge your battery at an amperage more than 1/6 the rated capacity of your battery. For example, it you have a 7 amp-hour battery, you should not charge it at an amperage of more than 1 amps. If you have an 18 amp-hour battery, you can charge it at a maximum of 3 amps. Therefore, most battery tenders offer charging amperage of from 1/2 amp up to 2 amps. NOTE: NEVER USE AN AUTOMOBILE BATTERY CHARGER ON YOUR POWERSPORT SEALED BATTERY. Although recharging seems like a simple process, as a general rule of thumb always wear protective eye wear and refrain from smoking as you are working with explosive gasses.
and I know this is blasphemy...but a nice website for you to consider reading about amperage and...beamers. there i said it. Please don't kick me
http://www.w6rec.com/duane/bmw/electrical.htm
and once again - just so you know - that when you do a jump from a car running - that battery from that car rates anywhere from 35-50 amphour, and when that runs through an alternator, the amperage signal is nearly quadrupled ranging from 140-250.
A motorcycle battery ranges from 10-15 amperage, in which a motorcycle alternator can push it to a max around 30-40 amperage....
You try putting nearly 6 times the amperage power through your system...and you will start smelling burnt copper and tie sleeves everywhere....so yes. you are lucky.
DO NOT JUMP YOUR BIKE FROM A CAR!
DON'T EVEN CHARGE IT WITH A CAR BATTERY!
And for heavens sake, don't boil the battery out of use by using a car charger.
There. i'm done now. Three edits in the making. Huh, looks like things haven't changed that much since my rusty crazy650.
[ This message was edited by: simonsez on 2006-11-20 21:27 ]