QR50 - Wiring

It's a bit early to be looking at wiring up the QR50, but since we are on lockdown and my workshop is a few streets away I have resorted to bringing stuff to the house to work on. It's good to bring the wiring indoors - it's a nice clean job that you can do at your desk in the study.

This is virtually all I have, apart from the toasted generator stator I showed you in another post. This is the CDI unit:

And here it is again with all that insulating tape removed. If you look closely, you will see that some of the wires have been cut very short:

This is the whole 'harness', minus the sleeving. There isn't much to wire up on a QR50, but it is not supposed to look like this:

Before we start though we need a circuit diagram. Through a lot of research, Honda parts lists, generic CDI system diagrams and looking at the charred remains of the original loom I have come up with this:

There's a lot going on in this diagram, besides the connectivity of the various parts. Let's look at the way the system functions:

• The Black and White wire (BW) wire is the exciter - it provides AC voltage to the CDI module
• The Blue and Yellow wire (UY) is the trigger - it uses the hall effect sensor in the rotor to tell the CDI unit when to fire the coil
• The kill switch earths the exciter coil through a second BW wire, preventing the ignition from working.
• The Green and Yellow wire (GY) is connected to a micro-switch in the rear brake lever. According to the user manual, the engine won't start if the brake is not applied, and there is a spring loaded lever to hold the brake applied while you start (this disengages as soon as you squeeze the brake). I assume (at this point) that the switch is intended to break a ground connection when you apply the brake, but that this has no effect when the engine is running...
• The Black and Yellow wire (BY) is the wire to switch the ignition coil.
• The Green wires (G) are grounds.

In addition to the functionality, I have used this diagram to indicate cut wires - each cut wire has a number (1 to 16), and each cut wire has a connector (male, female or double female). The harness layout is shown in a simple sketch with rough dimensions; I have shown a length against each cut wire and summarised these to determine the total length of each colour. This list, along with the list of connectors, tells me what to order. I have followed Honda's practice of using the same 1.0 mm² wire throughout.

I'm going to use original type Japanese 3.2 mm bullet connectors throughout. These work beautifully and are protected from the weather - but you must select them according to the wire diameter.

Here are most of the parts we need:

First, I am using some tube crimps and solder to extend all the wires from the CDI unit to match the only remaining original wire, the ignition trigger. This is often tricky, as 40 year old wires are often too dirty to solder; this one has been OK, probably thanks to all the insulating tape.

I've protected these joints with heat shrink sleeving. I bought a selection of 8" lengths in various colours from eBay, and very useful it is too.

This is the CDI unit, finished with sleeving and boots as the original was. That large boot with the section change was made from a short length of heat shrink sleeving, partially shrunk over a small bottle of glue:

The parts list calls for a harness from the CDI unit leading up to the headstock area - this connects in the two handlebar switches.

Here's the finished stator:

Now I have the bike partly assembled, I can lay the harness out on it to see where the parts are routed and to ensure that I have sufficient length in each of the harness parts.

Charlie's Shed - Winding Springs

It's fun when new jobs come along, as each time you have to discover new techniques & tools to achieve the goal.

This one is about spring winding. Over the years we've had a few elderly bicycles (and of course the dear departed CycleMaster), often with rod brakes and it transpires that the return springs for the handlebar levers are not available - even our old-school cycle shop cannot find them anymore.

These levers use a special torsion spring wrapped around the lever, which hooks around the lever and bears on the handlebar. The springs are handed, and we have an example:

It's a torsion spring of about 5 turns, with a double bend at each end; I plan to wind a few of these springs, of both hands. I don't plan to plate them; I'll probably paint them black. The plan is to bend one of the right angles into one end, wind the spring and then make the other bends. Whether we can do that without heat remains to be seen, and the spring will need to be tempered to reduce the residual stresses left after the bending operation.

First though, I need to establish some dimensional parameters in order to make the tools to wind the springs. The micrometer shows us the wire is 0.060" diameter in it's plated condition; I was able to buy some 0.055" piano wire easily from eBay.

Click the picture to get a link to this calculator. Based upon the number of turns and the wire diameter, the calculator tells me that I need to have a mandrel of 0.344" diameter, which I will turn up on the lathe:

The mandrel will need a 'flag' to trap the first end of the spring, like this:

I've welded this in place:

The flag needs a notch to trap the first end of the spring

You can use the notch to form the first end:

Forming this way does not produce a neat square end like the original.

However, in the interest of learning I made a prototype in the lathe. I turned the lathe in gear, power off using a tommy bar in the chuck key slots. I formed the spring using hand tension only and produced this first spring. the second end was formed with pliers:

Not too shabby; I know that the mandrel is still too large as I planned to avoid taking the finishing cuts until I had welded it so it is no surprise that the spring is slightly too big - I am on the right track though.

In the next few pictures, I show my latest method. Not wishing to put too much time into tooling for two springs, I took short cuts until I could prove the method. If I can successfully and repetitively make these springs, I might make some better tooling.

I folded a bit of 1.5 mm sheet over the wire to make a tensioner. This is notched at the rear so the tension goes into the lathe tool post, and it has a 5 mm hole at the front, so the grub screw retains the tensioner in place without adding to the wire tension; the other three grub screws tension the wire. There is a piece of 6 mm square bar under the tensioner, packing it up. The mandrel is the correct size to the calculator.

From the top down, you can see that I've put a notch in the front of the tensioner. This is to to guide the wire onto the mandrel at the appropriate point.

Here you can see the wire going onto the mandrel:

I think I've cracked the method for bending the springs now. These are bits I've developed:

The first prototypes proved that I needed a better method of forming the bends, as the method of bending with pliers wasn't producing crisp bends. These two pictures show what I did:

So these are the two prototypes I've made, left hand and right hand:

Here's one in situ, showing that the wide end is way too long. It's supposed to fit around that pedestal the the bar is mounted on:

Chained for Safety

Various bits of my W/NG are supposed to be chained in place to avoid loss in the field, like the fuel and oil caps and the toolbox lid. Having looked around for the right sort of chain, and not found anything suitable I set about making some.

I figured that I could weave figure-8s from brass wire and solder them together, so I made a hairpin jig out of some 4 mm rod, thinking this would give me a nominally 1/4" chain by the time the loops had sprung apart:

Holding this in the vice, with enough of the legs protruding for me to make a couple of links, I set about weaving:

And some more, pushing down and extending the legs as I went:

When I had made 5 links, and pushing them links down the legs was getting difficult, I stopped and cut the ends of the links. I cut twice on each link, to make sure the loops were equal and that the ends butted down onto the middle wire. I used a regular hacksaw for the prototype:

Here's how they look:

I wanted each link to have a right angle twist, so I twisted them with pliers:

Next job, hook them together and close them up

Make a lot more...

And here's the petrol cap chained in:

Here's the oil tank cap with its original chain, sent to me by Jørgen Andersen of the AOMCC, all the way from Denmark: