Chris is building a 1966 Triumph TR6R as a Bobber, and reached out to the British Motorcycle Mechanics Facebook group for some advice with the wiring.
He is going for the Electrex World STK-102D kit.
Here is a copy of the Electrex World STK-102D-DC instructions:
Here is a copy of the Electrex World STK-102D-DC troubleshooting guide:
The STK-102D-DC kit covers many models of bike in a single kit.
There is a great video on YouTube which was made by Classic British Spares
You can see the video by clicking here:
Handily it covers some of the gotchas and things to look out for when fitting.
So kudos to the guys over at Classic British Spares for taking the time to put this together!
Keep it Simple
In order to help Chris, and keep things simple (a Bobber is usually just the basics, and pretty much stripped out and clutter free) I have added a few bits along the way to help him wiring it all up.
We can swap these out for other makes/designs as Chris buys the bits he needs, but at least this will get the ball rolling.
Chris wants to wire the bike up negative earth, which is no problem at all when you are starting from scratch.
One thing I have done is produced a wiring diagram with a negative wire running from front to back of the bike – there is a massive advantage in doing this, and making it part of the loom, as it means you rule out any unreliability associated with bad earths, or trying to get power through rust, paint, powder coating, paper gaskets, loctite, clutch cables, steering bearings and speedo drives.
For the sake of spending an hour running this wire now, it means you rule out a massive variable, and make troubleshooting really easy in the future. Well worth doing!
Here is a simple diagram that shows the negative wire with the splices for the individual components – I usually have a 12 gauge cable to handle this – a 2mm² cable will handle 25 amps which is more than enough.
When you splice into the cable to feed the negative to an individual component, you can use a lighter gauge cable that is rated for the maximum current that particular part will draw.
For example, the turn signals can have an 18 gauge cable – 1mm² will handle 8.75 amps and be more than enough.
Even an ultra bright 10 watt bulb will draw less than 1 amp.
Here is a diagram cover the design for the negative “bus” that runs from front to back, with the splices to feed the individual components.
If I am using connectors on a bike, I like to use crimp ones – they are much better at resisting the issues associated with vibration versus the solder connectors – a reason why they are used in the automotive industry as well as in aviation.
I personally really like the Deutsch connectors – they do a couple of different sizes:
- DTM Series are the smallest ones – they will take 16-22 gauge cables and are rated to 7.5 amps.
- DT Series are slightly larger – they will take 14-20 gauge cables and are rated to 13 amps.
These are my preference, as there are several benefits:
- You can strip them down to just the crimped pins, which is handy if you need to pass them through smaller holes and grommets
- They are IP68 rated so good to prevent water and moisture ingress
- They are available in a huge selection of different “ways” (1, 2, 3, 4, 6, 8 and 12)
- They are easy to crimp and assemble
- They feel like quality that will last
- The packages are small and dense in their design – many of the alternative connectors are big and bulky which makes them difficult to hide away.
When I am making up looms and harness from scratch, I like to minimise the number of connectors I use – ideally using them only at the point the cables plug in to the components themselves.
This feels contrary to what they did back in the 60s on bikes, where you seem to run into connectors for the sake of it – these are potential points for moisture ingress, terminal corrosion (the dreaded verdigris) and ultimately failure.
If I am splicing like in the case of the negative bus (covered above) that I like to run from front to back of a bike, I like to bare the cable using wire strippers where I want my splice to be, I then twist the junction wire around the bared section, solder it, and use an adhesive lined heatshrink sleeve over the top which will protect the joint from moisture ingress and provide decent strain relief.
I feel that mechanically twisting the cables as I do, and then strain relieving them so well means there is zero risk of a soldered joint becoming dry or failing – I have certainly never had a failure in many years.
Here are some pics of my splicing procedure:
When I have finished making the harness, and I wrap the whole thing in cloth tape, you’d never know there is a joint there!
The tape I like to use is Tessa 51608 fabric tape (it is also known as fleece tape)
It’s nice and furry, sticks well to itself and doesn’t come unravelled. It gives a great OEM look.
I have added a small 4 way blade type fuse box – these are tiny, and very low cost.
Somewhere like Auto Electric Supplies is a great UK supplier for these.
They are less than £10 to buy, and the one i like has a little LED next to each blade fuse which tells you when it is blown. Brilliant.
A single red wire back to the battery – 12 gauge or 2mm² is fine.
I think it is a great idea to have a Battery Voltage Monitor, and for a Bobber, the SparkBright unit is a great choice
These are low cost, small and easy to place (a simple plate next to the ignition key is the way to go)
Here is an example of the SparkBright I fitted to a cafe racer – it is under the seat next to the ignition key.
It will obviously tell you when your ignition key is on (a green light) but importantly it will also tell you what sort of condition the battery is in in terms of charge/discharge as well as that the alternator is doing it’s job when the bike is running!
Chris is still unsure what to go for in this respect, so for now I have just selected one of the most common switches available. These are used all throughout Jap bikes, and are very low cost to buy.
As I said before, if we need to swap this out for something different and amend the wiring diagram to suit, we easily can!
So this one is from Venhill – but you can get them on ebay for about £10
Of course they are readily available for all the usual suspects as well as eBay too!
Here is the wiring diagram for the VEN025 switch
Chris has gone for one of the beautiful Headwinds headlamps.
The particular one he’s got has no pilot light (sidelight) in the bucket. It’s just an LED lamp with dipped beam and main beam.
Also, with a nice, spun, highly decorative headlamp like this, he will not want to drill it for switches and warning lights, so I have kept all that stuff out of the diagram.
The headlamp and tail light will come on with the Ignition Key switch, and you can toggle from dipped beam to main beam on the handlebar switch.
I have added the Electrex World SW01K key switch to the diagram.
This is a great choice, as it is a double pole switch that makes it suitable for a separate ignition system like the Electrex one (also for Magneto bikes)
I have also seen these on eBay for around £5
One set of terminals is closed when the switch is on (powering lights etc)
The other set is closed when the switch is off (grounding the CDI ignition) which cuts the engine.
Here is the wiring diagram for the SW01K key switch
So here is the wiring diagram for Chris Smith’s 1966 Triumph TR6R Bobber with the Electrex World STK-102D kit.
Custom Wiring Diagram (Electrex World) – Chris Smith PNG 3066×1841
This is available as a PDF too – it can be downloaded here.
Updated for 2023
There was a recent enquiry from Dave C regarding the headlamp and tail light coming on with the ignition.
That is what Chris Smith asked for, as he was decluttering his bike as much as he possibly could.
However, many people would choose to have the lighting switchable with a separate switch.
Here is an updated Wiring Diagram that includes a separate toggle switch:
Custom Wiring Diagram (Electrex World) – alternative PNG 3066×1841
This is available as a PDF too – it can be downloaded here.