Motogadget M-Unit Blue, Rick's Regulator/Rectifier and ignition switch

Sounds like it might be hooked up incorrectly.

On the solenoid, two of the four pins are always hot (they get power from the solenoid wire) and were originally designed to provide outgoing power to the ignition switch and then incoming power from the regulator/rectifier.

The other two pins go to the yellow/red wire and green/red wire, used to activate the solenoid.

With the plug removed from the solenoid and everything hooked up to the battery, use your multimeter to identify which two pins have 12V. The other two are the ones that should go to the yellow/red and green/red wires (doesn't matter which goes to which).

Can I completely dispense of the two wires that would have originally been connected to the always hot pins? Assuming I can, but just wanted to verify. Also, concerning the two pins that are not always "hot", are they only hot when starting the bike?

Yes, you can ignore the always-hot pins if you have other provisions for the ignition switch and regulator/rectifier.

The other two pins will only be hot when the bike is on and the starter button is pressed. For your setup, one of those two pins should be grounded and the other should go to the STARTER output of the m-unit.

Sonreir™ said:

Yes, you can ignore the always-hot pins if you have other provisions for the ignition switch and regulator/rectifier.

The other two pins will only be hot when the bike is on and the starter button is pressed. For your setup, one of those two pins should be grounded and the other should go to the STARTER output of the m-unit.

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Pretty sure that the plug was simply installed 180 degrees out. I will hook everything back up shortly and let you know. Thanks a lot for all the info/help, really appreciate it.

So as suspected, the connector for the starter solenoid was installed 180 degrees off. The bike now turns over, but still doesn't start. S0, here I go with a couple more questions.

1. After attempting to start the bike for a couple minutes, I decided to verify that I have power at the spark units as well as the coils. The coils checked out good with +12v, but the spark units are only registering approximately 3.5v each. Is this normal, seems as though they should also be getting 12v.

2. Concerning the carbs, which were off the bike for over a month, is there a need to prime the bowls and if so, what is the procedure to do so?

Thanks,

Drew

1.) Yes, they should be at around 12V. You're measuring at the black/white wire?

Is there an updated forum to this problem? I have a 1980 cb750f and am trying to figure the wiring. thankS!

jegabbi said:

Is there an updated forum to this problem? I have a 1980 cb750f and am trying to figure the wiring. thankS!

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Start up a new thread with the issues you're having and we can take it from there.