Charging issues

[chillman]

i get 12 volts on the battery while revving it up . What should it be. Above 5000 rpm?

[chillman]

I just replaced the regulator rectifier last year. And I replace the battery every two years. (Yuasa batteries)

[silverstrom]

You should be near 14.5 V at 5000 RPM.

Make sure you have a good ground at the regulator/rectifier. A poor ground will result in a lower voltage. I've dealt with that here many times.

[chillman]

Thanks!!! For the guidance !!

[smokamoto]

Our bikes use the 47X regulator/rectifier which were also on the FZR400/600s and Virago V-twins. Horrible units that constantly fry. Best to upgrade to larger units like the R6 that have actual cooling fins, at least! Not sure there’s enough room though...
My RZ is on it’s second 47X unit.

[silverstrom]

Same one on 1986 -90 RZ350, TZRs, etc. Widely used and generally not problematic if the rest of the system is maintained. If yours is constantly frying you have another problem.

[smokamoto]

Glad you’ve had good service using & diagnosing them. Here’s my experience - I’ve checked wire block connectors for melted wires, stators & grounds good, charging outputs correct, they just don’t last - for me anyway. I upgraded my ‘88 FZR400 to early R6 unit after two OEMs & one aftermarket failed.

I rode my RZ500 that I just got back together to the Yamaha shop I used to work at and my parts manager friend of 40 years said back in the day we used to sell two to three a week of the 47X reg/rect units. As as a Yamaha tech in the late 70s & early 80s I replaced many of them.

As always your results may vary - and as silverstrom said check the entire system, don’t just change parts.