Motorcycle Repair: yamaha 1100 1981, regulator rectifiers, regulator rectifier

Question
Chris,
We have a 1981 Yamaha 1100 Special that we had off the road for about 15 years. We had it out for one short run, but it does not seem to be holding its charge. The stater and rectifyer appear to be okay. At the moment the mechanic is changing the voltage regulator,air filter and reverse lighting device(hard to find one of these). Is there any advice you can offer us? We realise we are working with a dinosaur. Thanks


Answer
Hi Augusta.
 I hope that the battery that you are using in the bike is new and not the old one that was in it when the restoration started.  If it is not a new battery, then replace it.

You could have a couple of things wrong on the bike.  You could have a hot ground (where a direct power lead is grounding out) somewhere, a short in the charging system, bad connections, bad stator or even, and least likely, a bad regulator/rectifier.

The stator test is simple.  Start the bike and test the power level at the battery leads while it is running.  You should be getting 13-15 VDC.  If not, then the statoer is bad.
 If you pull the cover off where the stator is located and it smells like burned wiring or burned plastic, then that confirms thatthe stator is bad.

 Regulator/rectifiers are not known for going bad that often, so I don't believe that you problem lies in that.

Good luck.
FALCON