Topic: clutch must be in to start bike ?

[Wisconsin Rider]

I have a 1974 550-4 that I have been bringing back to life.
It was a "curbside find" that was in pretty rough shape.

I replaced the handelbars, and rebuilt all of the switches as well...
but now the only way to use the starter motor is to disengage the clutch...(pull lever in)

I must have something cross wired...any ideas where to look ?   

                           

[mgbgt89]

Neutral switch isn't working. Does the bulb light up when it's in neutral?

[BobbyR]

Neutral switch isn't working. Does the bulb light up when it's in neutral?

+1

[cookindaddy]

I have a 750K8 and there is a sensor switch in the clutch handle housing that senses when you have the clutch pulled in to let you start the engine, even if it is not in neutral. Mine was stuck closed so that it could not tell that I had pulled in the clutch. This is an override to the neutral switch so that I could only start mine when it was in neutral. Hard sometimes on a 750 when the oil and the engine is hot. When I replaced the broken clutch sensor, I can now start the bike when it is in gear (without hunting for neutral) if I pull in the clutch.

[HondaMan]

I have a 1974 550-4 that I have been bringing back to life.
It was a "curbside find" that was in pretty rough shape.

I replaced the handelbars, and rebuilt all of the switches as well...
but now the only way to use the starter motor is to disengage the clutch...(pull lever in)

I must have something cross wired...any ideas where to look ?   

                           

Those bikes have a 'Safety Circuit' that requires EITHER: clutch be pulled in OR bike be in Neutral, before the Start Solenoid low side receives Ground when the button is pressed.

Often, the O-ring around the neutral switch has shrunk from age, which lets the switch slide in slightly more than it should. When this happens, they both leak a little and the ball detent does not lift up far enough at Neutral to turn on the Neutral switch.

This 'Safety Circuit' was started in 1973 on the 550 and 750. If you want, you can bypass it entirely, making it like the 1972 and earlier bikes, where the Start button works anytime the key is ON.

[Wisconsin Rider]

Thanks for the info...The neutral light does work, but it must not be communicating that to the starter.

Now that I know that it was built that way as a safety feature, I can look further into it.
(I was concerned that I might have connected some wires incorrectly)

I appreciate the good info !     Thank You !!!

[Fritz]

There's a silicone diode between the neutral switch and the starter relay that prevents the neutral light to come on whenever you pull the clutch.
If this diode is missing, the starter switch circuit does not close without the clutch being pulled.
This diode is located right above the regulator. Sorry, currently I don't have any pics.

/Carsten

[mystic_1]

Sorta like this.

mystic_1

[TwoTired]

The 74 Cb550 has the Starter Safety Module that Hondaman refers to.  The simpler diode circuits happened on later models.
The diode (s) may be inside the SSM.  But, they are not easy to access.

Cheers,

[Fritz]

The 74 Cb550 has the Starter Safety Module that Hondaman refers to.

Ooops. I should've read with more care 
The shop manual has a schematic of the "Start Motor Safety Unit" featuring three diodes, two resistors and two transistors. I guess Honda had a reason (besides costs) to replace this in later models with a simple diode that can be diagnosed and changed if tested bad.
I guess that one can substitute the whole safety unit with a single diode (e.g. 1N5408) between the "green/red" and "light green/red" wires with the negative terminal of the diode connected to "light green/red"

[HondaMan]

The 74 Cb550 has the Starter Safety Module that Hondaman refers to.

Ooops. I should've read with more care 
The shop manual has a schematic of the "Start Motor Safety Unit" featuring three diodes, two resistors and two transistors. I guess Honda had a reason (besides costs) to replace this in later models with a simple diode that can be diagnosed and changed if tested bad.
I guess that one can substitute the whole safety unit with a single diode (e.g. 1N5408) between the "green/red" and "light green/red" wires with the negative terminal of the diode connected to "light green/red"

Yep!

[Wisconsin Rider]

Wow ! I am always impressed by the wealth of knowledge shared on this site.
My old 550 would not be anywhere near as nice as it's starting to be without these posts.

Thanks Everyone !!!