Low voltage at ignition coils

[Forkster]

Hey guys,

I’m rebuilding an abandoned 1980 CB750 Custom and I got some questions around the voltage at the ignition coils (this is my fourth bike rebuild).

Measuring at the coils itself, I only get 2V and 1.8V. The coils are 12.4kohms (perfect) and the wires are all good. I barely get any spark.

So, tracing back, what should I be looking at?

Any insight would be appreciated

 

[kammery]

Hey guys,

I’m rebuilding an abandoned 1980 CB750 Custom and I got some questions around the voltage at the ignition coils (this is my fourth bike rebuild).

Measuring at the coils itself, I only get 2V and 1.8V. The coils are 12.4kohms (perfect) and the wires are all good. I barely get any spark.

So, tracing back, what should I be looking at?

Any insight would be appreciated

First check avalble voltage at the battery . 12 volts is what it should be . Unplug the ignition coil connector . Locate the 12 volt wire . Connect the voltmeter . It should read 12 V . Do you have test light with a bulb ? You are going to do what is called voltage drop test . Connect the test light to the 12V Feed wire . Wether it glows or not is not important now . The ignition key must be on . Connect one lead of the voltmeter to battery positive . The other lead touch to 12v feed at coils . The meter might read say 10 volts . This is the voltage drop . Move the lead connected to the 12v feed to the next connection till the meter reads 1/2 volt or less .That will help you find the poor connection .