Well maybe but since we are discussing using a battery from a vehical that runs (we'll assume a working charging system) that units battery will be charged And even a stock battery after a bit of cranking will have the XS charging system going as hard as it can for a while. Thing is no matter how big the battery is the XS will only put out it's meager what? 100 watts of net charging. So the small motorcycle cables will deal with that just fine. Lawn tractor or other small equipment battery also good jump candidates. Always good idea to use a battery charger to assure it's in top shape first.Well, no I'm not wrong. Just because you've always done something doesn't mean its right. Wire size, component heat dissipation, component load are all based on amperage calculations. Not Voltage. Car/truck systems are built to handle WAY more amp load than a motorcycle. You wouldn't use 14-2 for a 30amp circuit in your house would you? I don't know maybe you would, I wouldn't. I also wouldn't use 750CCA battery normally used with 00 cables on a motorcycle of unknown condition that was only designed to run a max of roughly 210CCA @1.4A constant load with 8g cables. I only use cable size as an example, but NOTHING in these 37-52 year old motorcycles was designed to handle the amps of a modern car or truck. And yes I realize the guys start their bikes with car batteries occasionally and usually nothing goes wrong, but I would not encourage anyone of unknown skill level to do it bikes of unknown condition as it could cause problems that otherwise could have been avoided. For those of you who seem to be under the impression that amperage is irrelevant, I challenge you to swap the + battery cable in your car/truck with one the same size as the one on your XS (8awg) and see how long it lasts. Or better yet, if amperage doesn't matter go put a 14awg cord on your dryer.
Also, kero is not cheaper option for everyone. Its near impossible to even get NO1 kero in large swaths of the US and where you can get it, it's $13 dollars a gallon at the big box store.
PS I like the old mechanics way of thinking. I've given a near identical speech many times.
IE look a gift horse in the mouth before you start spending lots of dough on it.