K6 UK/US wiring harness differences?

[Underdog1]

Hi guys,

The wiring on my US K6 is old and crusty and as I'm doing a full rebuild I want to replace it.

As standard this bike had a headlight that was wired to be on, I have since bought a UK spec switchgear which will allow me to turn the lights on and off. My question is - are the UK and US harnesses themselves any different? I've seen a reasonably priced harness on eBay from Z1 parts (a supplier ive seen mentioned on our yank sister site) for ~£80 delivered, but just want to check it's the right fit before pulling the trigger.

The replacement part I've found is 3200-341-703 whilst CMSNL states the correct part number for a U.K. Spec K6 as 32100-341-900

[Mag1]

Hello, I think the only differences are as you stated, eg lights on all the time, think also that us bikes don't have parking or what they say side lights. I maybe wrong. There is forum member on here which makes up harnesses, Alan?. Hopefully he or someone will tap in, get in touch with him and he will put you right.

[Mag1]

http://www.alans-electrics.co.uk/, see link. He is known as bigal on here.

[Underdog1]

Hello, I think the only differences are as you stated, eg lights on all the time, think also that us bikes don't have parking or what they say side lights. I maybe wrong. There is forum member on here which makes up harnesses, Alan?. Hopefully he or someone will tap in, get in touch with him and he will put you right.

Im wondering whether those differences exist in the switches solely, would make sense I suppose. Just had a look at that website and it's well over double the price of the ones I'm looking at..

[Chris400F]

There was a recent thread about CB550 wiring (http://www.sohc.co.uk/index.php/topic,12019.0.html) where it was noted that there was a jumper wire somewhere in the harness that did the lights on bit. I'm thinking it's probably something similar with the CB750.

[Bryanj]

The difference in the looms, UK to US is the extra wires on the US one to service the "running lights" in the indicators (Blue/White & Orange/White) which you leave disconnected as they aint legal in UK. The US switches put the rear light on in "Park" but there is no front one. You need to connect the headlamp sidelight/park as that is a legal requirement in UK even if the headlamp comes on as well at the same time

[BigAl (Alan)]

The UK switch gear can be utilised, obviously the USA head light has a sealed beam unit (no park/city light as image) Double check the spec of the looms for sale at £80.00. Most will be for USA models K3,4,5. Its not suitable for the K6 USA/UK model...starter safety devices are different, one is 2 wire the other has 5 wires.

I hope the above helps

Alan

[Underdog1]

The UK switch gear can be utilised, obviously the USA head light has a sealed beam unit (no park/city light as image) Double check the spec of the looms for sale at £80.00. Most will be for USA models K3,4,5. Its not suitable for the K6 USA/UK model...starter safety devices are different, one is 2 wire the other has 5 wires.

I hope the above helps

Alan

Yeah it is advertised as a 73-75 harness but in the description it says it can work with a K6 if you have the switchgear which allows you to select high/low on the left and on/off on the right. There's no wiring diagram on there. I've emailed the asking about the starter safety so will see what they come up with.

Here's the harness:

https://z1parts.net/honda-cb750k-1973-75-wiring-harness/

If it won't fit the k6 starter safety then I'm wondering if it would be just easier and cheaper to bypass it?

[BigAl (Alan)]

The harness can be modified to suit the replacement switch gear. The other issue is the starter switch on the K3-K5 has 2 wires as the K6 has 3 wires, if your OK with electrics it should not be a problem

[Underdog1]

The harness can be modified to suit the replacement switch gear. The other issue is the starter switch on the K3-K5 has 2 wires as the K6 has 3 wires, if your OK with electrics it should not be a problem

Just heard back from the company, they said as long as I have the replacement switch gear the harness will fit without modifications, including the starter switch. Guess I'll find out soon enough

[BigAl (Alan)]

mmm...if you can get hold of the latest Clymer manual for the CB750 there are large colour wiring diagrams at the rear.  The K3-K5 harness would need to modified
Image of the 3 wire K6 start switch attached