battery draining question- honda cb360t

I have a stripped down honda cb360t (1976) that's used for trail riding.
There are no lights or turn signals on it. (there is a horn) anywho, when
the key switch is turned on (and the kill switch on the handlebars is on)
the battery voltage drops steadily, like there is a draw on it. When I turn
the switch off, the battery goes back up to around 12 volts. The bike kick
starts perfectly, and when it's running, the voltage does not lower. What
could drawing the battery? I've checked for any wires that would be grounded
out but find nothing. It seems wierd because when started, it holds the
voltage. Any ideas??

thanks,
walt

 

Your point ignition system draws power from the battery

 

The ignition system.

Next question?

 

thanks for all the responses. i knew the ignition draws from the battery
when the switch is on, and because it's an old shitty battery... it all
makes sense. i was looking for reassurance. the diodes in the rectifier
could be a culprit as well, a new battery first though makes sense.
thanks again,

walt