Motorcycle Repair: Electrical - 1971 Honda Sl350-k1

Question
When the key is on and the on/off switch is off, it reads over 12 volts and the neutral light is bright...all is good.  When I put the on/off switch to on...the voltage drops to about 8 volts and the neutral light gets dim.  I have read where this is normal to a certain degree but I think this is extreme.  Also...if I am wanting to start the bike and if it takes multiple kicks to do it...my neutral light gets dimmer quickly and battery seems to drain power.
Assuming my battery is good....and sounds like there is a bad connection or short....what is the best way for me to troubleshoot this?
Wish I could find a motorcycle electric expert in Michigan.
Thanks

Answer
Ken, your battery is bad....

It is holding a "surface charge" of 12v, but when you put an electrical load on it (Ignition switch ON to power the ignition system coils in this case), there is very little current/voltage left to run the bike properly. The cutoff voltage for the coils is down around 9 volts. When you repeatedly kickstart the bike, the permanent magnet rotor is continuing to generate a little bit of voltage to help the battery fire the coils. If you were push-starting the bike, it would have the same result.

You can't assume that a battery is good without testing it. They only last about 2 years in most cases, anyway. So, go buy a new battery, get it fully-charged and you should be fine, unless your charging system is not working properly.

Bill Silver