Author Topic: need to by pass ignition switch - how?  (Read 5715 times)

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Offline Scott

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need to by pass ignition switch - how?
« on: December 02, 2011, 03:17:57 PM »
Hello there
The CB750 1972 I picked up a few days ago has a dodgy ignition switch.  Is it easy to bypass this at the round plug by bridging two wires together.  I'm a bit reluctant to start bridging wires with out the correct info incase a stuff something up.
Does anyone know which wires to join together or am I better off waiting for a new switch to be delivered
Thanks for your time
Scott

Offline MoMo

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Re: need to by pass ignition switch - how?
« Reply #1 on: December 02, 2011, 03:41:19 PM »
Red in and black out will get you going...Larry

Offline Patrick

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Re: need to by pass ignition switch - how?
« Reply #2 on: December 02, 2011, 04:50:30 PM »
The Br/W also powers the Br wire to the taillight through the ignition, so you will have to account for that if you want a taillight. The switch provides power from red to black, then b powers Br/w inside the headlight bucket and the Br/w runs back to the switch to power the br. Neither circuit, br/w and Br, will be complete without the switch. You'll have to power them another way.

Yeah, I took one apart. Just because.

Patrick
1970 CB750 K0
1982 VF750S Sabre
1987 VT1100 Shadow
1979 Yamaha XS11
1969 Yamaha DT1B
etc.

Offline Scott

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Re: need to by pass ignition switch - how?
« Reply #3 on: December 02, 2011, 05:31:57 PM »
Thanks heaps
I tried to jump across the brown and red wires but nothing happened.
So I took the rubber boot off the back of the plug on both sides ( switch side and wiring harness side). the red wire was corroded and fell out of both parts of the plug.
Luckily I got a kit from that vintage conection place and just put in a new plug.
Scott

Offline Scott

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Re: need to by pass ignition switch - how?
« Reply #4 on: December 02, 2011, 05:33:48 PM »
Oh yeah just got back from my first ride ever on a CB750 ever.  Man good fun, love it.  Can't wait until tommorrow for a longer run
Scott

bollingball

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Re: need to by pass ignition switch - how?
« Reply #5 on: December 02, 2011, 07:31:20 PM »
About that burnt red wire is every thing stock coil headlight if not you may want to look into some relays to help out the load on your sw.
 http://sohc4shop.com/catalog/product_info.php?cPath=23&products_id=46

Offline Patrick

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Re: need to by pass ignition switch - how?
« Reply #6 on: December 02, 2011, 07:32:45 PM »
Or run a heavier gauge wire from the battery.
1970 CB750 K0
1982 VF750S Sabre
1987 VT1100 Shadow
1979 Yamaha XS11
1969 Yamaha DT1B
etc.

Offline Scott

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Re: need to by pass ignition switch - how?
« Reply #7 on: December 02, 2011, 09:03:10 PM »
coils are stock but not sure about headlight. I will have to investigate what globe it has