Motorcycle Repair: Honda CB 650 electrical, honda cb 650, stator coil

Question
Hi Chris,
I'm an allexperts contributor (skiing) but now for once I get to ask rather than answer. I have just been given a very nice low milage Honda CB 650- (1979) and it runs smoothly except for one issue. The bike runs on battery only- it drains the battery and does not recharge it. I have to disconnect the battery, plug it in, and then re-install. I'm an ok mechanic with cars but not cycles (yet). Does this model have a voltage regulator/magneto? What am I looking to test or replace, whats a good book to buy or web site that shows me how to do it?

Thanks

Tom

Answer
Hi Tom.
 Well, if my wife ever gets me back up north for skiing, I'll be coming to you.  But for now let's fix your bike.

All bikes have a power generation/battery recharge system  The older 1950's and older as well as the 2-stroke bikes all have a magneto.  This was replaced in later years, in 4-stroke bikes, with a stator coil.  They also have a regulator/rectifier which converts AC volts into DC volts.

Since the bike is not charging at all, the most likely problem is the stator coil, since regulator/rectifiers do not tend to fail that often.  You will need the manual to test the regulator/rectifier.  There are certain specs that you will find that the reg/rec has to be in compliance with along with the test proceedures for each component on the bike.

For the stator coil, start the bike and connect a multimeter to the battery leads.  It should show 13 - 15 VDC while the bike is running.  If it is less than that, then the stator coil needs to be replaced.

Good luck.
FALCON