Topic: Frankenbike 750 electrical challenges

[78whiteorbs]

Got a Frankenbike cb750 with some electrical issues.

I know the engine is a 78. The frame is a 76 but not sure what year the harness is. Thought it was a 76 harness but there is no starter safety module I can find. Where would this be?  So the bike starts and runs great that's the good news :-) . Probs are :

No power to headlight- No voltage on the fuse block on the headlight fuse either side or the tail light.

Brake light isn't working- running light works

Also e start isn't working . Continuity tests good to solenoid.Starter engages when bridging the posts. Not getting any voltage from starter switch when pressing the button. Not getting any going into it either.

Noticed a few things, clutch safety switch has one wire broken at the clutch switch. With this disconnect I am thinking it will not e start. Neutral light comes just fine .

My gut feels like the starter safety control module Or lack there of is causing some estart issues. Kicks just fine.

Should there be power to the headlight fuse when the
Ignition is on...?
There isnt.
This bike had no key so I am hot wiring it till the key comes in. Just twisting the red and black together..
Is there any need for the brown and brown/white wire . I was thinking that these are just for key switch positions that leave the tail light on and not essential.
really close . I have a wiring diagram but this bike isn't exactly virgin in the electrical department and I don't think the control pods match the harness year ( there is a headlight on off switch on the right pod)

I have no problems bypassing things on this harness if need be. Not trying to bring this thing back stock just need a brake light , a headlight ,and e-start would be nice too. Not to much to ask hUh?

[links56]

Sounds like you have power to the main switch at least. I will have to check out mine and see how its wired unless you can post a picture of the wiring schematic so I could look at it.

[78whiteorbs]

Ordered a key last night.

I have ran toggle switch before instead of keys when needed.
So theoretically running a toggle with black on one side and with the corresponding brown would give me juice to the headlight?  I have no use for the third key position(parking light).

I have tried a few variations and cannot seem to get power to the headlight and tail light fuses. Only the main fuse gets power.


I cleaned up a lot of connector contacts last night to no avail. The head light and tail light is all that's keeping me off the road. The estart would be nice too though..

Anyone have a pic of where the safety start module mounts and we're it comes off the harness?

[Don R]

When the switch pod was changed anything could happen, the headlight fuse gets fed from the switch the switch is fed from the main fuse if I remember right, follow the wire route with a test light and check at the connections.

[78whiteorbs]

I think that's what happened . I got the tail light/ brake light worked out and it was really a no brainer with ignition switch (simulation really waiting on the key to arrive had to twist them up)

If the Headlight power does feed from the ignition to the pod to the fuse then that's the problem.

[78whiteorbs]

I know guys build simplified harnesses with one fuse for everything on choppers and what not. This bike is far from stock and I am only running headlight , tail light/ brake, and ignition. Any harm in running one fuse for headlight and tail light, eg tapping into tail light power I would guess up the amps of the fuse and I get if it blows I lose all lights .

[78whiteorbs]

Have a sigma computer  for speedo ,and nc is a no turn signal state. Horn works!