TOPIC:

Hey guys, I have a 78 KZ650B. My battery voltage is 14.50 at idle and goes down when I increase the throttle. Why is this backwards? I also can't run on the highway. I am assuming because of this. Any help would be appreciated. Thanks.

If the battery is fully charged, you should still be able run on the highway for a little while even if the charging system is dead. If you can't, maybe you have a short that only develops when revving.

Also, if it is just the charging system giving out at higher RPMs, that is not uncommon. I've found some regulators that worked fine at low RPMs, but as you rev up, the voltage drops and you get almost no output from the reg/rec. That one usually gets people since they only check the voltage with a meter while the bike is parked, but it really needs a voltmeter on it while riding to check in all conditions.

Make sure you have an analog (needle) meter to read the voltage. Some digital meters go crazy when you tach up the engine because of EMI and they read gibberish.

If the readings are real: my guess would be the alternator output is weak, rectifiers are blown, regulator module is fried, or similar. It should be regulating at 14V.

The reg/rectifier and the stator are pretty much new. I've noticed it has done this with the previous set also. I haven't been able to run on the highway for a long time. It just seems that the voltage is backwards. I don't know what to do next. I guess I will check the stator output.

Also, I don't think we are supposed to have 14.50 volts at idle. Isn't it supposed to be a little over 12 ??

14.5 at idle is ok if you can get it. Most bikes can't unless you turn the lights off or have a really efficient aftermarket ignition. Like Bountyhunter said, make sure your readings are real and not an errant meter.