Topic: CB750K6 Front Brake Light Switch Wires Routing

[M 750K6]

Hi,

I have just found one of the leads to my front brake light switch had broken. The righthand one, just at the point it enters the bullet connector on the switch. The other lead was also weak.

It looks like they have been stressed from bending as the handlebars move. The two wires enter the main loom under the fuel tank. They seem to just exit from under the tank and make their own way to the switch. The black outer sheath ends just over an inch or so, before the bullet connectors. There may be a bit of interference from the throttle cables. My throttle cables are coming round the front of the steering headstock, to the left side of the underside of the tank. Is that correct?

I've repaired the switch connections. There is still plenty of slack in the brake light switch cable back to the loom, even when the bars are at full right turn. It seems it will only be a matter of time before it happens again?

To check it's routed properly, does anyone have a photo of how the wires route out of the loom through to the switch, round the throttle cables?.

[newday777]

That is correct as to the throttle cables going around the front of the headstock to the left side of the frame to enter just behind the coils.
You are talking about the brake pressure switch on the bottom triple tree?

[M 750K6]

.....
You are talking about the brake pressure switch on the bottom triple tree?

Thanks. Yes, that's the one.

[newday777]

The wires from the switch should not be behind the throttle cables.

[newday777]

A better view

[M 750K6]

Thank you. Perfect. I will look tomorrow, but I think the main loom and brake light cables are lacking that tie to the frame top tube, so the wires are coming out sideways more. That, or it has slipped backwards. Also, the sheath is self amalgamating tape on my brake light wires, so that might possibly result in all the movement being at the switch end, rather than perhaps slipping a bit within the looser sleeve your photos show.
👍

[pjlogue]

I had the same problem with wire breakage on the front break switch on my '76 750.  It is a stress point at the wire to bullet connector.  A short length of heat shrink tubing with inside glue (marine heat shrink?) will extend the life of the connector.  It is a flex/stress point that is also subject to weather.  wire routing should be outboard of the throttle cables so that the flex in the wire is distributed over a longer wire length as the steering head is turned.

-P. 

[M 750K6]

I took photos of how it was all routed, before I took the bike apart. I put it back together the same way. So I guess it had been removed before.

Took some photos today. 1st picture is the revised routing. The 2nd image is how I'd originally got it routed:

It doesn't stick out to the left as much now. But it does rub the inside edge of the tank...