Topic: 1975 cb400f silicon rectifier

[wilson11]

Hello everybody.On the left side of the bike when sitting on it, underneath the side panel is a very small part(about 1/2 inch square) with 2 wires leading to it.Honda calls it a silicon rectifier, part #31700-124-003. What does this part do in regards to the electical system?
 Thanks                                     

[aptech77]

Found some info...A silicon controlled rectifier (SCR) is nothing more than a rectifying switch. It does not conduct until its gate (a small third terminal) is triggered by a dc pulse or series of pulses.

[Bodi]

You mean the black plastic rectangular prism shaped object with 2 spade terminals coming from it that plugs into a matching socket?
This is the starter safety diode that lets you use the electric start with the bike in neutral and the clutch lever out. Without it, or if it is "open" (one way for a diode to fail) you need to pull in the clutch to use the starter. If it goes "short" (the other way diodes fail) your neutral light will be on whenever the clutch lever is pulled in but otherwise the starter will work as designed - in neutral or clutch pulled in.