Part 12. The wiring loom & electrical specs

We’ve already covered a lot of the thinking behind the electrics in part 6, and will test the viability of the chosen systems later on, but regardless of the theory, somebody needs to make the chosen electrics work by making a wiring loom to join it all together.

That person was never going to be me!

I seem to write a lot in this blog about not being able to do stuff myself; this part is exactly the same.

Cue Andy Woolrich of

Electro34 is a brand new motorcycle electrical engineering firm, handily in Old Stratford, a northern territory of the place most know as Milton Keynes – just 20 minutes up the road from me.

Andy volunteered for the job a while back and after the briefest of meetings to sound each other out, we agreed it would be brilliant to work together. Why? Well, we like the same stuff, we’re from the same era, we’ve both raced, we both love endurance racing and we both like doing things “the right way” (well, I do most of the time, unless it involves cheap paint).

Andy is a qualified electrical engineer that has a background working on things much more complicated than motorcycles – namely radar systems! It just happens that his passion for the last few years has been wiring 2-wheeled stuff. He’s doing enough of it now that it’s a good time to make it into a business.


And yes, the 34 in Electro34 does mean he’s a Schwantz fan! He even owns quite a lot of Schwantz’s original RGV bodywork, which may or may not be featuring on a very special 570cc project of his own… I’ll leave it to him to tell you about another day!

Here’s the full list of things that Andy will be wiring together;


  • 2* x 12v Skyrich Lithium Ion battery (YTX14 equivalent) wired in parallel to double capacity. *planned, currently single battery.


  • Dyna – ignition (the old style one using the mechanical advance)
  • Dyna – rev limiter
  • Dyna – coils
  • Taylor leads
  • Stock starter motor
  • Bandit 600 Starter solenoid


  • Separately switched –
    • Switch 1 – headlight/both tail lights
    • Switch 2 – spotlights/both tail lights
  • 1 x 1157 fitting rear LED bulb (brake & tail light circuits) running with both light circuits activated
  • 1 x 1156 fitting rear LED bulb (number plate light)
  • 1 x H4 LED headlight (16W measured actual power consumption)
  • 2 x H3 LED spotlights (tba)


  • 1 x Kubota single phase permanent magnet alternator (Kubota Part number 15531-64017)
  • Maximum output 14A at 5200rpm
  • Minimum charging speed 1800rpm
  • Maximum operating speed 5600rpm
  • 1 x Kubota matched regulator rectifier (Kubota part number 15531-64601)
    • 14.5V DC output +/- 0.5V (2 redundant connections – battery charging lamp and a “load” connection)
Simple, small, reasonably light and 14A of charge at 5200 rpm on tap, although at lower rpm we still need to do some testing – should be ok though, LED lights are frugal, around 1/7th of the current of conventional lights (on paper…)




  • GSX-R slabside Rev counter
  • Backlight LED for these clocks
  • Original Oil pressure light switch feeding LED indicator light
  • Battery level warning indicator – a single dash mounted large LED that continually signals voltage condition using 3 different colours and 3 different flash rates. It will signal everything from battery near death to battery overcharging.
Basic. Ideal.
Basic. Ideal. Left hand light is for low oil pressure, right hand light blinks the charging/battery condition at us using different coloured lights and blink patterns.


  • 30A Circuit breaker as main switch with push-break to isolate electrics
  • R6 Kill switch and starter switch gear
  • 2 x 2 position kill switches used for main & twin-spot lighting circuits


  • 4 way fusebox – fused circuits
    • Headlight
    • Spotlights
    • Ignition
    • Clocks/warning lights

The loom itself is taking shape and already well advanced. Watching Andy work proves that whilst this is a job most of us would think of tackling, we’d be well advised to have a think if that may be the best way forwards! His work is easy to write about, because it’s so nice to watch it happen. The results are clean, beautiful wiring.


I pulled up a chair alongside him during an endurance soldering session and picked his brains about what makes the difference when tackling wiring such as ours. Some of the answers are as you’d expect, some less so.

In a bullet point list, here’s what Andy from electro34 thinks are the key points in making a loom great.

  • Keep it simple!
  • Plan it down to the last wire/connection before you start.
  • Keep the amount of wire to a minimum.
  • Keep the amount of connectors to a minimum.
  • Keep the cables away from trap points.
  • Build the sub-assemblies (sections of loom to/from switches/lights/components etc) first.
  • Solder and crimp each connection. Good soldering is essential, when done properly it will not make the connection inflexible and troublesome as often repeated on the internet.
  • Annotate the wire colours and connections you have actually used as you go so your plan gains all of the actual detail as you make the loom.
  • Take pictures as you go!
  • Operating an understandable colour coding of wires to certain types of load or device is helpful to trace faults/repair damaged looms on race bikes.
  • Buy the best materials you can afford – weatherproof sealed connectors are Andy’s favourite and used on our Katana loom. (see pic)
  • Use larger Amp rated wire than you need – we’re using 32A thinwall.
  • Military spec connectors will not achieve anything other than spending your budget faster if you buy good connectors in the first place!
  • Finally – stripping out a standard loom for a custom/race/restoration build is something we’ve probably all considered, here’s why it isn’t such a great move
    • OE loom design rates speed of installation in the factory over the ideal cable routing.
    • OE looms do not use high quality materials – they’re built to a price.
    • OE looms over 20 years old use materials that are simply nowhere near as good as available today – our 32A thinwall wires are a classic example of lighter, higher rated and more flexible material which is put to good use in our race loom.
    • By carrying empty connections and dead end wires in a stripped out loom you’ll introduce multiple and often untraceable fail points.

Andy shared his thoughts on how electrics are treated as part of the average project plan – “it’s the last thing the project builder thinks about – I’ve seen and worked on bikes which have had massive amounts spent on them, only for the wiring thrown on at the end to resemble something you’d expect to see on a field bike!

Given the late nature of my call to Andy to get his part of the project done, I ashamedly resemble that very person. Although I am not guilty of bodging the wiring, I am guilty of treating it like the last job on the list “get someone to throw a few wires on it, it’ll be alright…!!!”

I learnt it’s not a good thing to partition the electrics as an “easy/quick job” amongst all the other difficulties of the build.

Try finding someone that will build you a loom quickly. Take a look around, see how many auto-electricians with proper motorcycle experience exist, then see how busy they are and get a price/waiting time…it’s not a pleasant experience; fancy a 9 month wait for a £1000 loom?…that’s a real lead time, and a real price, based from first hand feedback on a project a good mate of mine has that needed electrics. Frightening.

I’ve already joked with Andy (who at the moment at least promises not to be as expensive or as unavailable) that he’ll be retired to the Bahamas in 5 years, I think he’s going to be that busy.

I’m glad we got him to wire the Katana up before that happens…