Topic: Start Circuit Diagrams, CB550 vs. 550F, Do I have it right?

[fhoffman]

In trying to diagnose problems on my CB550, I found that a previous owner had made some electrical repairs based on 550F wiring.  In reviewing the full wiring diagrams for both machines, and pulling out just the start circuit, I believe the following to be true (see attached diagrams):

Using the convention that current flows from power(plus) to ground(minus), on the 550F the current flow through the start button is toward the solenoid, while on the 550 the current flow is from the solenoid (opposite).

Whereas on the 550F, the closing of the neutral and clutch switches simply grounds the current allowing the solenoid to activate,.... on the 550 the closing of the switches actually opens the contact between the yellow/red wire and black wire, removing a short around the solenoid, thereby allowing the solenoid to activate.  I think this is true, but I don't understand the role of the ground wire (green) entering the "starting motor safety unit".

Obviously, the 550F system does the same job, but is much more elegant.  Keeping in mind the differences, I am considering simply finding a properly rated diode and getting rid of the safety unit box.  Any suggestions?

Frank Hoffman, Cleveland.   

[oldbiker]

Hello Frank, where did you get the diagram for the CB550 showing switching for the starter safety box?  I am sure there is a fault in it, since if the switch is closed connecting the black wire to the green/red wire at the same time as the clutch is operated then there would be a dead short circuit from battery positive to ground. Honda would never have allowed this to happen. It would certainly be simpler to follow the Cb550f circuit as this does the job adequately. If you are not keen to keep the bike 100% original and do not feel able to sort out the starter safety box, this would be the way to go.

[bryanj]

The one prior to the safety circuit grounds a solenoid wire via the bars with the solenoid powered the later puts power to the wire to the solenoid INSTEAD of to the headlamp with the solenoid grounded. Hope that makes sense