Powering electric vests.

How many extra amps are there on these old bikes?

I have a 1977 KZ650B1. The regulator and rectifier are new items from Oregon Motorcycle, the battery is fresh this year as well. I get a consistent 13.8 volts charging at 4,000 rpms and the battery has yet to drop below 12.7 volts after a ride or when it's just been sitting a week or so.

I have a Aerostitch electric vest that draws 5 amps. Can the old girl handle the extra draw or am I going to wind up stranded?

If you think about it this way, 5 amps is the equivilant of say 3 running lights, which is something people do all the time with no problems. So I/d say you're safe. You just can't go overboard with lots of extras like cb/radios, lots of lights, police sirens, etc.

Is everything, other than the charging system, stock?
If so, then it should be able to handle it.

If you are running a Dyna S ignition with 3-ohm coils, you'll be getting close to the 20-amp limit, so keep extra fuses.

The best way to tell is put a voltmeter on the battery while it's running with the vest on. Above 2000 rpm you should be above 13v.

If you idle for a long time, you probably want to turn the vest off.

The bike is CLOSE to stock. I have some aftermarket turn signals on it and a Candlepower halogen headlight conversion kit. Otherwise as far as electrics go it's bone stock. I'll hook up a lead and try the voltage test...