Question1972 Honda CB750 K2 in storage for 20+ years. Took it apart to clean it up, removed headlight bucket and since all wires are color coded, no sweat putting it back together. Just one thing, there is a RED wire in the main harness going into the headlight bucket. Not hot with key on. I don't know what it is for! I have wiring diagrams for 1971 and 1975 bikes, but they are not quite the same. Help!!!
Need a wiring diagram for this bike.
AnswerI have looked over the schematic for the CB750 K2 available at the link below and I can't see any sign of a red wire in the headlight bucket.
http://www.oregonmotorcycleparts.com/diagrams.html
NOTE: You need to be careful when looking at OMP's drawings because it is sometimes difficult to tell the orange & red apart.
The actual orange & red wires are easy to tell apart so I don't think you will have mixed them up. In Honda wiring orange wires are for the left turn signal and red wires are for the battery positive (always hot) circuit.
There is a red/yellow wire that goes to the Start button, but if the solenoid is plugged in it should have 12V relative to ground except when the Start button is pressed.
It is also possible that a previous owner modified the harness and added that wire or replaced a damaged wire with it.
I don't see any wires on the schematic that aren't supposed to be connected to something. Do you have an other wire in there that isn't connected? That might give you a clue...
