Topic: CB750 K4 Electrical Question

[JeffK]

I have swapped out the wire harness on my CB750 K4. Everything works (finally) and I am left with one issue. The left hand control turn signal switch is defective. I can gently move the thumbswitch tiny amounts when it is in the center (cancel) position and the turn signals go off/on and not together either so I am saying throw that out (it isn't original anyway) and get a new one. To be clear I am buying a new left hand control piece. Can anyone help me with where I can buy one that work well? I also need any advice people have on getting the wires back through the handle bars.

Thanks everyone,

Jeff

[BenelliSEI]

Jeff..... not sure where you are located. In Canada, I usually hit EBay first. It will give you the best options. Buy a new replica switch. Yamiya in Japan makes nice stuff, Vintagecb750.com is my favorite in North America. David Silver Spares?
     On the old stuff the wrap and the wires are so brittle you will have a hell of a time pulling them in. Assuming you used a replica K4 wiring harness, get the matching switch. K0, K1 and K7 and K8 are different. I think you can use a 1972-76 switch. Your old wires will stick in the bars. Assuming it’s garbage, cut them off at the bar centre and then pull hard from the switch end. Next I usually slide a bit of mechanics wire up from the centre clamp hole, hook the end and tape it securely to the new wire ends. I have a pot of the yellow grease electricians use when they pull wire bundles into conduit, but any grease will do. Coat the new wire bundle and it should slide in easily. Good luck. John D.

[jaytee-nz]

Yep - Yamiya has good stuff with excellent service as does David Silver in the UK.
The only brand that most people steer clear of is Emgo.

[JeffK]

Yamiya it is.

Thanks Ben/JZ

[JeffK]

I thought I might have a go at cleaning up the left hand control a little before I bought a new one and I did just the basic take it apart and spray contact cleaner on it and now it operates perfectly.

Anyone else having blinker button issues bear in mind you might want to try a cleaning.

Jeff

[HondaMan]

An addendum: the K4-5-6 switch is different from the K3 in that the K3 does not have the spring-loaded "lane-change' momentary contacts: instead it only switches to the left or right with a snap like the earlier ones, while still having the Hi/Lo headlight switch aboard. The K0 switch is unique. The K1/2 originally had the Turn Signal Beep 'kill' button on the bottom of it, but the ones available now often do not.

The K3 and later versions have lots of wires, hard to feed thru the bar. Run a mechanic's wire up from the middle of the bar to the slot at the switch, then use black plastic/vinyl electrical (not duct) tape to lay the connectors as flat and slim as possible to pull it all back to the middle. Takes a while: maybe Jim Beam will help...?

[my name is nobody]

To add/related....If you have bare handle bar, clean inside of bar with high pressure water blast, compressed air dry, and follow up with wd40 and a final air blast to get the excess out.

[jgger]

If the original wires are still in the bar then connect a wire or stout nylon sting to the wires BEFORE you pull it out. That will be your pull wire in place without fishing (or cussing). Attach it to the  new harness that has been coated with your lube of choice and pull it back through. EZPZ!

[JeffK]

I got my wire through the handle bar. There are a lot of wires on that control and the handlebar is sooooo damn small but I got it through there.

I have all the wiring disconnected and through the mounted H/L Cup. I am going to start final electrical mounting/connecting now.

Thanks guys,

Jeff