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CB750 72' Intermittently Runs, Lights dim wont start.

KirinC

CB750 New member
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Hey guys, new member here.

Just recently picked up an old cb750, was told motor work was done, compression is spot on and plugs look just fine.

The bike ran great the day I got it, and it will still fire up via Kick Start but won't run long. I can start the bike up, and it will run for a good 30 seconds.

From there, it starts to slowly drop in RPM's, until it dies.

I noticed the lights are VERY dim when I turn the key to 'on' trying to re fire it, and nothing happens. The funny part is, I can come back into the garage the very next day, turn the key and the lights will be bright as day, and it will fire RIGHT UP. But again, only for a short lived 30 seconds, where it dies yet again and the lights dim. In addition, I noticed that the choke doesn't make much of a difference when the bike is running.

Can anyone shed any light? I found a suspicious connector with '193' on it, two fuses, and one plug with four male 'spade' connecters. It has three wires running to it, one red, one yellow with tracer, and one black (ground). Anyone know this plug/relay? I believe it has something to do with the starter, but am not sure. When I unplug it, the lights don't work.

Could this be related to the ignition too? Any input is welcome, pics soon to come.

Culprits: Petcock? Electrical mishap?

This thing was screaming the day I bought it..Now, it sits. :banghead:
 
Sounds like the alternator, battery is recovering a bit overnight.

Thanks for the input, I'll look into the charging system today. Found a suspicious ground yesterday that I'm also looking into.

More input is welcome, I'm going to try my best to figure out how to upload pictures
 
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