Author Topic: Electrical Question 1973 CB350F  (Read 484 times)

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Offline zcb350fb

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Electrical Question 1973 CB350F
« on: August 30, 2018, 07:39:08 AM »
Could a head light on/off/high-low beam control switch breaking cause the main fuse to blow.

A few months back, main fuse blew while the bike was running when I switch the headlight from off to high-beam. I replaced the main fuse and the bike was fine for a month. then a month later, the head light switch broke. (the little black plastic piece that slides between off/on/low/high inside the switch cracked in half beyond repair.) I was able to get the headlight to stay on low beam and it worked. then the fuse blew a month later and I replaced the fuse again and now fine. so basically I am wondering if all of these fuse issues stemmed from the failure of the headlight off/on/high-low switch? Where should I begin to look?

I also checked and cleaned ground under the seat. are there any other grounds that I should check?

I never had fuse issues before. I have had the bike for a year and these issues never arose until now
1973 cb350f

Offline flybox1

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Re: Electrical Question 1973 CB350F
« Reply #1 on: August 30, 2018, 02:35:16 PM »
The switch is a known weak spot in the wiring.    A few things you can do....
Cleaning every connector on the bike, and replacing any weak wiring spots is the first step. Also check the back of the fuse box...you'll want to replace anything that looks like it got hot/melted.
Then...
Hondaman sells a plug n play harness to relieve the voltage strain on the switch.  IIRC it will work on the 350F
or...
Add a relay so the light runs directly off the battery
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

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1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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Offline zcb350fb

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Re: Electrical Question 1973 CB350F
« Reply #2 on: August 30, 2018, 05:02:44 PM »
Got it. Thank you for the advice!
1973 cb350f