Motorcycle Repair: 1973 CB750K, state rectifier, engine rpms

Question
Bill,

I have a problem with my charging system.

First things first.

New battery.  Nice sealed battery not a crappy $35 acid battery.

New rectifier/regulator from Carpy (Steve Carpenter)

http://www.cb750cafe.com/products-page/lighting-electrical-gauges/solid-state-re

Stator reads at .9 or 1.0 ohms.  Clymer manual says it should be .2 ohms?  I checked some videos online and most say .9 or 1.0 is fine.

Coil reads at 7.8 ohms.  Clymer manual says it should be 7.2.  Is my reading too high?

I assume the rotor on this bike is static; I don't see anywhere to test it.

Do I have a short somewhere?

Thanks,
Ted

Answer
Ted, you can use the troubleshooting charts at www.electrosport.com which also has a "known troubles" section for quick reference.

www.sohc4.net has tons of CB75-SOHC info, including a whole troubleshooting chart.

My info is showing 7.5 ohms for the field coil.
Stator leads should be below 1.0... noted at .4 in a Honda TSB.

Rotor has no "test" points, unless it is loose on the end of the crankshaft due to a sheared key.

CB750 CHARGING RATE CHART

This charging table provides charging system ouput for various engine RPMS during day (headlight off) and night (headlight on) conditions.  This data can be used to test and adjust the output of the charging system.

Engine RPM   Night Riding - Amps   Day Riding - Amps   Battery Terminal Voltage
1000          -0.5          0.7          12.0
2000          0.0          1.0          12.4
3000          2.4          1.0          13.2
4000          1.3          1.0          14.5
5000          1.0          1.0          14.5
6000          1.0          1.0          14.5
7000          0.8          1.0          14.5
8000          0.6          1.0          14.5

From the sohc4.net site.... some of the tech links are down now, though.

Bill Silver