FH - starting on the brakes

 Now that we are waiting for the tyres and we have the rear mudguard off, we can have a look at the rear brake. For reference, here's the drawing from the parts book:

First glance suggests everything is in order. The springs are all in place and don't look distorted at all; the adjuster is there with the two little mushrooms; there are no cracks in the shoes or the plate.

The shoes look old; they are worn, but not down to the rivets, but they look a bit greasy and glazed. This is the leading shoe:

This is the trailing shoe:

The drum is starting to see wear from being recently wheeled around and used a little:

I'm going to clean these up and see what the engagement looks like using the sandpaper technique. That will let me explore the adjustment and remove any greasy deposits to see if I can improve the performance before I commit to relining the shoes.

I've documented how I do this before, but it's essentially a long strip of 60 grit emery tape stuck to the brake drum with double sided tape. You then back off the adjuster, refit the brake plate and the wheel spindle, and spin the brake plate in the drum.

You then apply the brake with the lever so that the shoes contact the emery. The result is that the linings are reduced in the areas where they are high and this improves the fit of the lining against the drum. In this case, the exercise showed that the linings were already a good fit against the drum, but were clearly rather glazed.

We'll do the same at the front, and test ride it again.

FH - revising the plan

 Today I learned that my chosen front tyre was out of stock and wouldn't be delivered for six weeks - I needed a new plan.

Instead of building the wheels and leaving the bike rolling but tyreless, I'll rebuild both brakes and test them before I touch the rims. That way, I'll be able to get the brakes sorted and still be able to test them, albeit on old tyres. I'll only ride it across the yard, and I'll be able to sort out several other little jobs in the meantime.

To start with, I've been looking at the rear of the mudguard. The seat hides two of the bolts:

Or at least, it does if the seat is mounted in the wrong place. The mounts on the frame are slotted, and if you push the seat forward it not only closes up the ugly gap behind the tank, but you can get those bolts out too!

FH - getting on

 It's really time to get on with some woodwork projects, but I have a few minutes passing by the workshop where I can get some jobs done. The first one is a strange problem with the brake light on the Square Four, which has stopped working. This appears to be down to me replacing the battery in its box and knocking off the live feed to the brake light switch from the fuse box. Easily fixed fortunately.

That strange contraption in the picture is part of the air filter for the Huntmaster. The filter box, or at least the top half, is behind it. I've poured straight 50 engine oil into the top and its soaking through the gauze ready for me to put the element back in the filter box and the filter back on the bike.

We'll leave that to drain for a bit and fit it tomorrow.

On my short ride round the yard I found that I could not get the bike into gear - not because of the gearbox at all but because the footrest was too far forward and the gear lever was too low - I just couldn't get my foot underneath the gear lever to put it in first.

You have to remove the exhaust pipe to get to the nuts that hold the footrests on, but that's easily done and the situation is soon remedied.

I've also oiled the side stand pivot, and I've ordered the rims, spokes, tyres, tubes and rim tapes.

Gulp.

FH - first ride

 Well, a little trip to the workshop today to prepare for a woodwork project resulted in the usual diversion to a motorcycle activity, in this case a bit of time on the Huntmaster. I needed to move everything out to get the table saw ready and that gave me an opportunity to roll the Huntmaster off the bench and out into the yard.

Confirming the starting technique, that of tickling it until fuel flowed onto the drip guard, showed that it starts easily with the choke on - actually first kick. Riding it across the yard shows it engages gear quietly and drives without any horrible sounds. It pulls really well, but the timing side footrest is too far forward and the gear lever is too low.

The brakes are useless. There's far too much lever movement and no bite. They might be covered in grease, they might be glazed, who knows. I will order the rims, spokes and tyres and pull each wheel apart for refurbishment.

Pumping the tyres up shows there's not much height in the centre stand - I've got around 3/8" under the rear tyre.

The side stand is stiff.

It looks great.

FH - toolbox, charging and other progress

 The toolbox is back on:

In other news, the primary case now has oil and the FERC is no longer dripping oil all over the bench. The oil tank now has a felt wick for the chain case feed:

It's made from a strip of felt, 10 mm x 10 mm x 25 mm:

I made this short video to record the fact that the battery is now charging after we re-polarized the dynamo and updated the RB108:

Doesn't the engine sound great! I got it started a couple of times using Easy-Start, but it only ran for a second or two. Playing around with the fuel supply, I eventually tickled it for a long time - until I had a flood under the carburettor. It started and ran perfectly, but needs choke - perhaps I am starting to learn the technique?

To report on a couple more things: the clutch cover screws are a bit short of thread - there is a 1/16" unthreaded section under the head - cutting the thread on that bit will allow them to go fully home. I've put shake proof washers on them for the moment.

I've failed to improve the front brake - any more turns on the adjuster just lock it solid. It will have to come apart.

The oil banjos on the rocker box are in good shape - they have a lot of contact area though, so they have to be very tight to seal. I've smeared a bit of Wellseal on them which seems to have done the trick.

Number plate next, then the instrument panel and lastly the fuel tank.

FH - a few more bits

 It's New Year, and I have a couple of railway turns, a party, visitors, and not much time in the workshop. I've done my last firing turn this season, on the 1943 ex-WD Austerity 2-10-0 no. 90775. A cracking thing to thrash across the countryside in the dark:

All in all, not much workshop time. I sneaked this in:

That's it, a bit of sleeving to tidy up the HT cables.

I've also replaced the secondary chain. There's 100 pitches here, as per the parts book, but I'm a bit mystified as to why the wheel is quite so far back in the slots.

I wonder if I have too many links in the primary chain...

(Updated April 2025: I did, but there was another problem. The parts book suggests the primary chain should have 73 or 74 pitches corresponding to the size of the engine sprocket. It turned out that I had 74 pitches and I had the sidecar engine sprocket which has 22 teeth - so not only was my primary chain way too long for the sprocket but the sprocket was wrong as well!)

FH - another tiny part, and a list...

 A tiny part that takes hours to make mainly because I made it twice to get it right - the linkage from the brake lever to the brake light switch, made from a piece of 1.5 mm thick stainless steel.

So what's next? There's a few things I can think of at the moment:

1. There is a leak from the inlet side rocker box oil banjo, but other than that the engine is finished
2. The primary chaincase has no oil
3. There's a dummy secondary chain fitted, and the end of the FERC is not fitted (and nor are any of the grommets).
4. There's nothing restricting oil flow to the FERC, but apart from that the oil system is finished
5. The dynamo is not proven to charge; the instrument panel wiring needs reworking and the ammeter doesn't stay in it's hole but other than that the electrics are finished
6. The 1/4" screws retaining the clutch dome are either too long or are supposed to be fitted with shakeproof washers. They are actually correct at 3/8" long 1/4" BSW, but it looks like they could have a bit more thread than they have...
7. None of the frame greasing points have been attended to yet, including the one for the new swinging arm bushes. Actually, the two grease nipples for the steering head are missing - not that they will do a lot of good, because the felt washers around the steering column are also missing!
8. The number plate has no numbers
9. The rear section of the rear mudguard is missing a bolt, and the hole it goes through needs enlarging
10. The front brake hasn't been adjusted
11. None of the fasteners have been checked for tightness
12. The wheels and tyres are still untouched

That's it for the moment.

Charlie's Shed - polarising the dynamo

 The need for this post arises because I have wired the Huntmaster negative earth. The dynamo that came with the kit is probably the original dynamo which of course will be expecting a positive earth system.

What's a dynamo 

A dynamo is an electrical generator that provides a direct current using a wire wound armature moving in a magnetic field following a principle discovered by Michael Faraday in 1832. It needs a mechanical commutator to turn alternating current into direct current since the rotating armature generates a current which changes direction as it moves through the magnetic field. An important principle as far as we are concerned is that the faster the armature rotates, the more voltage and current is generated by the machine. Similarly if the magnetic field strength is increased, the voltage and current will also increase.

How does it work 

In the motorcycle dynamos that we are looking at, the armature consists of a number of coils of wire wound around a stack of sheet metal shapes. The wires are terminated in a number of copper strips at the end of the machine arranged into a cylinder. The magnetic field is provided by a coil of wire wound around a suitably shaped metal structure fastened into the inside of the machine. The engine rotates the armature and a current is generated providing a magnetic field in the field coil. 

You will note that the magnetic field is provided by an electrical coil, and consequently you can imagine that the machine will not work unless that magnetic field is present when the engine starts. This is one of the issues we have to address. 

When the dynamo starts it is disconnected from the rest of the electrical system by the cutout in the regulator box and consequently won't start to generate electricity. In practice the field coil pole piece remains magnetized at least partially, after the machine was last used and we call this residual magnetism. This residual magnetism provides sufficient field strength to induce a current in the armature as it starts to revolve. Of course as the armature starts to revolve it generates a voltage which raises the field current which in turn increases the magnetic field, which allows a higher current to regenerated - and so it goes on. The voltage will carry on rising and in practice is limited by an external voltage regulator which takes effect by limiting current to the field coils.

Why do you re-polarise it

In a world where a motorcycle dynamo is perhaps not used every day, or the dynamo is moved from one machine to another perhaps having been bought at an autojumble or perhaps having lain around for a very long time since it was last used, it's functionality maybe compromised by a residual magnetism that is in the wrong direction or is so weak that it is virtually non-existent and the machine will not work. 

Therefore we need to have a method of generating that residual magnetism or changing its direction. Changing the direction of the residual magnetism might be necessary because you wish to rewire the machine for negative earth or perhaps because the machine for which your dynamo or specified rotated the dynamo in the other direction than that for which you wish to use it.

How do you re-polarise it?

Repolarizing the dynamo is quite straightforward and is just a matter of providing a current in the appropriate direction through the field coils. If you disconnect your dynamo, and provide a temporary cable from the battery terminal (that is not earthed) to the field terminal on the dynamo, you can repolarize the field coil by touching the wire on the field terminal momentarily. That should be sufficient to change the polarity of the residual magnetism or to generate it if it has seeped away. 

The temporary cable is not really necessary. Disconnecting the wires to the regulator reveals the green field coil cable and a brown and white cable from the ammeter. This brown and white cable is actually a battery cable, passing through the ammeter from the battery. Therefore, touching this cable to the field coil cable will polarize the dynamo correctly.

FH - voltage regulator

 One of the jobs on the list is to make the dynamo work. During the wiring up process I decided to make the bike negative earth to allow for fitting of things like USB chargers and other modern accessories, on the basis that this bike will become the universal machine. To that end, the dynamo will need to be repolarized, more of which later.

Another thing that I need to do is to fit an electronic regulator to match the VRLA batteries I have fitted. The late Ariel four-strokes were fitted with a Lucas RB108 regulator, and we will replace the inside components of one of these with a V-Reg 2b from AO Services here in Norfolk.

First we remove the aluminium cover, bending back the tabs and pulling out the inner parts of the regulator:

There are two steps to removing these bits. First you can undo two nuts under the Bakelite board to release the solenoids. You will also need to remove a single screw that retains the frame of the regulator.

The next step is to cut the wires and links leading to the four terminals. It's easiest to cut these to remove the obstruction of the solenoids before you take a large soldering iron to the terminals and release the little bits of wire that are left. You can then open the terminals ready to receive the wires from the new regulator when it's time to re-solder.

The V-Reg 2b has a couple of options for retaining the unit to the base; there are two bolts supplied which fit neatly into the old solenoid holes. The next job is to route the wires to the appropriate terminals and solder them up. I like to use an old-fashioned wire lacing technique to make a small wiring harness inside the unit. The lacing is wax coated linen thread tied with a clove hitch and reef knot to hold the wires together.

All that remains is to put the cover back on and close up the aluminium tabs as best you can. Alternatively you could use some hot melt adhesive to hold the cover in place.

FH - getting there

 A few minutes in the workshop moves the project on a little bit: the speedo drive locating pin has arrived from the AOMCC gearbox man:

It fits in this hole:

A look at the carburetter reveals that the float chamber gasket is actually there, but that the drip shield is a little distorted and a bit loose, which probably caused the spitting back. The main issue, staring us in the face (and highlighting the perils of long-term projects) is that the carburetter needle is still in the box of bits!

The engine idles now.

By the way, I have changed the 210 main jet to a 260:

A couple more problems are revealed - the inlet rocker oil banjo is loose, and the magneto earth button doesn’t work. The inlet banjo is an easy spanner job; the cutout requires a bit more investigation.

FH - a little more progress, and a big step...

 Well there's been a little bit more progress today. First off, I've finished the second of the finned exhaust clamp bolts:

Secondly I've been talking to people in the club about tyre sizes and whether I can get my desired tyre (Avon RoadRiders) in the size that I want. Having a look at the distance between the tyre and the chain guard reveals around 3/8" to 1/2" but also that this tyre, an Avon SM Mk11, is actually a 325-19. The front tyre, a Dunlop TT100 by the way is a 90/90-19 or 3.60-19. They are both from the 1980's.

I am hoping to buy Avon RoadRider tyres but unfortunately they are not available in the right sizes for this bike. The options appear to be to use a 100/90-19 for the rear (Avon's recommended replacement for a 350-19) and a 325-19 (original size) or a 90/90-19 for the front.

The next bit of progress is very small - it's just a P clip for the front brake cable. I've attempted to adjust both brakes but right now the front tyre is in the wheel clamp.

Lastly and very quietly and secretly I have hooked up the temporary fuel tank to the carburettor and started the bike. Unfortunately it will only start using Easy start, but at least it starts and runs. There may be some problem with the fuel supply or with the float bowl. It runs and returns oil and it runs nice and quietly so now I know that I have the HT leads the right way round, and the oil system is working properly, and the valve timing is correct and the ignition timing is more or less correct though it does spit back through the carburettor.

I think we'll have to wait 'til Monday to have another chance at it, but sleeping on it and looking at some of my pictures suggests that the float bowl gasket is missing. This will give you an air leak in the pilot fuelling circuit...

FH - exhaust clamps

You might remember that I brought some exhaust clamp screws from Draganfly that were the wrong size - my fault not theirs. One of the jobs I have on the list is to make some new ones and that's what we're going to do today.

The clamps are 5/16" CEI and have this 45 degree feature on the plain side:

I bought some 0.445" 303 stainless steel hex bar to make some new screws. The picture below shows the first one, prior to parting off:

I put the prototype screw in place to determine how long the hexagon needed to be in order to get access for the spanner, marking it with a Sharpie:

Here's the finished screw, parted off, faced off and provided with a tidy chamfer:

Lovely. Fitted with a dose of Copaslip.

I just need to make another one!

FH - head steadies

 A couple of hours in the workshop yesterday saw a few little jobs closed off. This was the worst:

Access is not easy, but the secret is a short open spanner.

The head steadies are now fitted with full size 5/16" nuts, which entailed lifting the rocker box (twice) to get them in.

Next up was the timing side footrest, which wasn't fully tightened up - doing that enabled the exhaust fitting to be completed on that side, with the exception of the finned clamp.

I fitted the speedo cable, to find that the locating pin in the gearbox was missing. The AOMCC gearbox man has them available.

I spent a while poking around under the instrument panel, where the ammeter has lifted out of the position and the cable routing is poor:

I've almost fixed these problems, but the ammeter is still out of position and the wire from the lighting switch to the dipswitch is too short; the feed from the ammeter to the indicator relay is badly routed and consequently too short, and the indicator relay terminals are almost impossible to reach.

The instrument panel is going to have to come off again.

FH - speedometer

The chronometric speedometer that appeared with the FH kit is definitely not Ariel – I was told it is from a police spec AJS Model 31 CSR! The rim has a 3/8" piece removed from it which looks very tidy, definitely not a bodge – maybe it’s to allow a police workshop to remove the rim for recalibration easily? I have no idea if it works or not. 

So – in order for it to become a S467/195, which I believe it needs to be to suit my ’58 Huntmaster/FH, it will need:

• An overhaul, including resetting to zero
• A new dial
• Probably a new rim.

Lastly it looks like the male thread for the lamp is spinning in the case – I guess it was swaged in or something, so that will need sorting out too.

As usual, I sent it to Russell Smalley at Chronometric Instrument Services - he's done all my speedos since the SQ4. His quality of work is excellent and very fairly priced.

It came back in about a week, thoroughly packaged:

It's got a used dial and needle, so that the appearance is in keeping with the odometer wheels. It's had a mechanical overhaul, new seals and rim, and a new bulb holder thread swaged in to the case:

Here it is going into the dashboard:

There's a stainless bracket I made for the indicator relay - which in this position makes it fiddly to fit the cable. I think there will be a bit more development needed here! 

FH - inching closer...

 The day seems to have disappeared again without too much workshop time but at least I've got a little bit done. 

The choke cable is now terminated to the right length, with a new nipple at the carburettor end. I didn't have the flat nipple that goes into the lever unfortunately and I didn't fancy making one on the lathe but I did have a little tiny one that goes in the choke slide.

There's not much to see here but at least we have a throttle slide and a choke slide that move independently of each other and don't have any slack in the cables.

The next little job is to make a couple of 5/16 CEI bolts to retain the finned exhaust clamps. Here I'm reducing some 0.445" stainless hex bar to the appropriate diameter for the bolts I need.

They're going to have a chamfer feature where they mate with the clamp - here is the chamfer on the clamp itself. When I have cut the thread on the bolt I will work out what the height of the bolt head above the clamp face needs to be:

That's all for a bit. I've got a 10-hour turn on the railway tomorrow which won't finish until after 11:00 at night, and then my grandchildren are coming for the weekend. Hopefully we will get the speedometer in the post either tomorrow or Saturday, so they'll be plenty to play with next week. I'll order the V-Reg2b voltage regulator as well, so we can convert the RB108.