Topic: 1975 CB550 - Need To Make A New Wiring Harness - Wire Gauge?

[campbmic]

Hey everyone! I have a 1975 CB 550k "cafe racer". Over the years the wiring harness has been cut to pieces and hacked up so I need to make a new one! I don't have turn signals and only use the kick start so I'm going for a pretty basic design using this diagram

http://www.chopcult.com/forum/showthread.php?t=16239

I run the bike off of a small 12v 7.5A gel battery. I'm pretty good with a multimeter, soldering, and working out wiring diagrams. However, I don't know anything about about wire gauges. I know wires that go directly to the battery are usually a heavier gauge.

Can anyone give me some advice on what gauge wires should be used at different points in the harness? Thanks for any help and let me know if I need to provide more info!

[przjohn]

I use 16 GA Primary Wire from an Auto Parts Store.

You can also get some of this stuff, it comes in all different sizes and works well for custom harnesses.

https://www.ebay.com/itm/1-2-Black-Ultra-Split-Wrap-Wire-Loom-10-Feet-wiring-harness-heat-resistant/312341152620?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

[campbmic]

I always thought the wires that connect to the battery terminals were thicker gauge. Can I use 16 gauge on the whole thing? Thanks for the response!

[BomberMann650]

The wiring to the starter and ground are something around 8-10ga.  Minimum size is dependent on amp load.

Iirc the "m-unit harness kit" from revival cycles used a lot of 14ga for lighting.  18ga for control signals.  (Not needed with an m-button circuit)

Some 12ga for the ignition and whatever motogadget sent for their main power strap.

[Tim2005]

Are you aware that David Silvers sells a new pattern wiring harness for the 550 at a decent price?  Making up harnesses is really time consuming, especially getting all the cable lengths just right, and buying all the wires in the various colours can be rather expensive too as you have to buy longer lengths of each, so I'd definitely consider buying a complete one.

[campbmic]

Good idea, Ill probably go with just getting a new harness then. I might even just repair mine. I took a look at it today and its not as bad as I thought. Thanks for the idea! Theres actually a bunch on ebay even new repro ones

[scottly]

Hey Michael! Haven't heard from you in a long time! Still using the ignition coil I sent you? I still have a chuckle when I think about how everyone blamed your issues on pod filters, when it was a cracked plug wire arcing to ground. 
Scott

[HondaMan]

Honda used 19 AWG equivalant size (in metric) for the Black Ignition circuit on the 550, and smaller wire for the switches and lamps. The headlight was also 19 AWG. The thick Red/White wire to the battery (from the start solenoid) is slightly smaller than 14 AWG. The starter cable (and battery ground cable) is 8 AWG in a thick vinyl jacket, looking much like a 6 AWG size.

If you build your own, try to use TXL wire. It will survive the conditions on the bikes better than common vinyl or PVC-jacketed stuff, or the very common "appliance wire", like MTW.