Topic: Starter question

[krksquared]

Anyone know how much current the starter motor pulls on a 75 CB400F? My starter button is becoming intermittent. I took a look at the schematic and it looks like the starter motor gets its power directly thru the switch. That's asking for trouble in the long run - and at 48 years I think that's a long run  I just might see a relay in its future. Just so happens I have some relays rated at 500 amps used in a Tesla Roadster...

[bryanj]

No it doesnt, the switch operates the starter solenoin behind the lh cover

[Deltarider]

Anyone know how much current the starter motor pulls on a 75 CB400F?

From memory around 120A.

My starter button is becoming intermittent. I took a look at the schematic and it looks like the starter motor gets its power directly thru the switch.

That's practically impossible. The wires would melt immediately and the switch too.

[MauiK3]

Starters on most things that have them get their energy from the starter solenoid.

[Bodi]

As has been explained, that switch just powers the starter relay (solenoid). But the relay coil inductive load does cause a tiny spark at the switch contacts on release, and that eats away at the contact.
The switch is likely unserviceable by now. The plastic parts turn to fragile brittle crap after some decades. So if it works, I would avoid touching it.
It switches +12V to the headlight when not starting, disconnecting the headlight and connecting the starter relay when pushed. Only reason I can think of is to reduce battery load when starting.
The headlight current tends to overheat the switch (again, decades passing has corroded the contacts causing some resistance). I recommend bypassing that switch for the headlight circuit, it's quite easy at the junction where the pod wires connect to the main harness. Doesn't affect starting in my experience. But the kickstarter still works...

[madmtnmotors]

The contactors in the solenoid can degrade over time. The good news is the solenoid can be restored to like new condition with a little elbow grease.

[krksquared]

Thanks for all the responses. I'll check the solenoid. Upon further exam of the schematic, I see the starter switch vs the solenoid. For some reason, I thought the solenoid was the starter switch. Hasty read on my part. As for the headlight shutting off while starting - not on my bike. Stays on all the time. Looks like another "issue"...