Charlie's Shed - recovering threads

 OK, so this is a commonly available AJS/Matchless frame stud, used under the seat nose to unite the front and rear frames. I can get a replacement very easily if I want to, but what if it's a unique part? 

The object of this blog post is to illustrate how to recover a part like this in the workshop. This stud has obviously been loose at some point in its life as the thread is worn away beneath the frame tubes where the rear frame fits over the stud.

Start by stripping it out and cleaning it on the wire wheel. We are going to be welding some overlay into that worn area and we don't want anything contaminating the weld. When you have it clean, use a thread gauge and a micrometer to make sure of the pitch and diameter - it's quite easy to mix up thread pitches, and you will even get the wrong nut on a thread for a few turns: something you don't want to do with a thread cutting die.

It would be nice if we had some sort of facility for rotating parts like this whilst welding, but if you work towards yourself it is quite easy to do a quarter or a third of the diameter at a time: 

A few minutes on the lathe reduces the welding to a plain shank suitable for thread cutting. Since there's a little bit of the original thread remaining on the stud, it's easy to start the die to recut the thread.

A few minutes later and the stud is good as new.

AJS Model 30 - swinging arm spindle

 Tom gave me the AJS swinging arm spindle to look at - it's had an engagement with Mjollnir or one of his brethren at some stage and will not enter the bushes.

The micrometer shows the diameter of the shaft at the damaged end is around 1.005", up from the 1.000" specified diameter. The areas where the bushes bear are around 0.998".

It's far too hard to turn, even using a carbide tool, so I have set up the tool post grinder to repair it.

I've added a small chamfer at the damaged end.

Next step is to send it home for testing.

Charlie's Shed - USB charging port

 Lately I have been using my Beeline motorcycle sat nav which I won in a competition (Do you remember I told you about it a while ago?) and I have been worrying that it will flatten my phone batteries - consequently I've decided to fit the same USB charger as I have on the W/NG to the Huntmaster.

I buy these from eBay for about £15 - they are very nicely made.

The eBay description says:

• Square Dual USB Super Fast Charge + Voltmeter
• Input voltage: DC12V
• Monitorable voltage range: 6-30V
• Product material: ABS high and low temperature resistant flame retardant environmental protection material
• Qualcomm 3.0 quick charging standard
• Output voltage: 5V3.4A/9V2.5A /12V2A

I found that they seem to work perfectly well coupled to a six volt battery because of course I'm only looking for a five volt output from the USB ports. The voltmeter is quite useful if you can actually see it - but you use it for diagnostics not when you are riding your bike!

You have the option to fit these things with a bracket or a handlebar clip and they come with a length of cable and a fuse holder.

I wanted to fit the charger inside my left knee above the battery and in front of the toolbox and I made a stainless steel bracket to bolt underneath the dynamo regulator.

As you can see in the picture it's too low and you can't get the battery back in. I might modify this bracket or make a new one to give it higher and further in board to allow it to stay in this position:

Nevertheless I can wire it up and show it working:

Until I get around to making another bracket, for which I really need to remove either the seat or the toolbox or both, I will use the handlebar mount and fit the charger above the Monimoto, behind the toolbox.

AJS Model 30 - the 'what bits are missing' dry build

 A few days after the Model 30 kit arrived in Norfolk, it's outside in the street for a degreasing session which will help us understand what we have, what we don't have and how it goes together.

The main frame parts are all there and most of the big studs as well.

Some of them are not in great shape and will need replacing or building up with weld and the threads recutting. And option would be to buy a complete new set at vast expense but we are not there yet!

The centre stand, it's bushes, stud and spacer are all there:

Footrest bars, footrests and side stand are also there as is the spindle for the swinging arm – but the cotter pins appear to be missing:

We have two sets of fork yokes but unfortunately the steering head races are a bit worn. We will see if they need replacing later on:

AJS Model 30 - a new bike joins the family

 Well, his has been a long time coming. A few months ago, son Thomas & I conceived a plan to buy a project we could build together with the kids - to give them some hands on experience and learn some new skills. I wanted Tom to buy something he really wanted, and we looked and bid on a Sunbeam S7, a BSA B50, an A65 and looked at an Ariel NH (which was a very good deal but wasn't a project).

I'm delighted that we ended up with this, a 1958 AJS Model 30 - Tom says there is a poetical symmetry to it, since I had a 1957 example when I was at university which we sold soon after we bought our first house.

It's an eBay find, described like this:

• AJS Model 30 Project rebuild or spares.
• Frame and engine are 1958 model 30
• Was going to rebuild, but will never happen, so must go.
• Engine fully rebuilt by local AJS Model 30 club specialists 15 years ago, still turns over fine. Comes with AMC gearbox and clutch etc. and majority of all major parts to rebuild, look at photo and you’ll see what’s included.

Obvious things that are missing are the silencers, mudguards, speedo and rear shocks but if we really have a properly rebuilt engine for less than £900 we will have done well!

Main frame and wheels above and most of the rest of the cycle parts below. Siamese exhausts - a sidecar bike? The rear mudguard stay looks like one from the CS model; there's a chainguard, brake pedal, battery carrier and lots of other bits:

A box of bits, including a new looking set of engine bolts:

Another view of the same curtain - there are two tanks in the kit that arrived and we see fork legs, some very high bars, a set of yokes (one of two), headlamp shrouds, one of two headlamp shells, centre stand, a head steady, footrests, frame rails, sidestand, oil pipes, engine plates and covers and the toolbox:

A tidy 58/30 engine with dynamo, gearbox, oil tank, primaries and clutch:

We can't wait to get stuck in!

FH - update

 The FH has been the go-to bike recently, and it is shaking down again after it's 500 mile service. I'm getting on top of the carburation helped by Hitchcock's (or Amal's?) guide to tuning the Mk1 Concentric, and now that I have it ticking over with a #30 pilot jet and the pilot air screw 1/4 turn out, I might go to a #35!

It's flying along and looks great:

Notice that the rear wheel is nicely off the ground in these pictures!

The only problem is - it's still burning oil in little puffs on start-up or when taking off from a stop, not constantly. The head is going to have to come off again to inspect the guides which is a shame, because the leaks are cured...

Model A - carburetter needs some bits...

 The Model A uses an Amal 6/112 carburettor, often known as a pre-monobloc. The Type 6 carburettor has the pilot air inlet in holes around the body and is similar to the Type 76 - the difference is that the 76 is cast alloy and the 6 is cast brass; the later Type 276 has the pilot air inlet inside the bell mouth. The float chamber design associated with each of these carburettors is also quite different in that the earlier float chamber has the extension pipe banjo retained to the float chamber itself with a screwed joint - for the 276, the extension pipe banjo is a part of the float chamber casting.

Whilst the carburettor that arrived with the Model A is complete, it is also pretty tired. The slide is very bad, the main jet is missing and we know from experience that the needle jet and needle will be very worn as well. 

The specifications are listed here:

• Size: 1"
• Main Jet: 4/042-160 (still available new)
• Pilot Jet: none
• Needle Jet: 4/061-106 (still available new)
• Needle Position: 6/065, position not recorded
• Slide: 6/0524 - that's a #4 cutaway, or 1/4"
• Float chamber: 14/004

Folk with some experience of Amal carburettors will realize that these part numbers are used for the Type 76 and Type 276 as well - and are still available from Burlen Services, or Hitchcock's Motorcycles.

I put in an order to Hitchcock's for some bits and sent the body, jet block and jet block nut to Joe the Carb on the 23rd of July:

It came back from Joe on the 8th August with a cylindrical bore, a slide to match, and he has refaced the mounting flange so that it is nice and flat. It looks like it has been vapour blasted too:

Until I make up the cables there's not much else I can do with this carburettor (other than replace all the gaskets and fibre washers), so we'll fit it back on the bike and leave it for now.

Model A - brake plates

 There hasn't been much action on the Model A lately – I have been rebuilding the top end of the Huntmaster and doing a bit of travelling. However, here is a little interlude: some while back we painted the brake plates from the Model A ready for rebuild and last year I acquired a new set of brake cams from the Slovak Klub.

You can see from the picture how bad the originals were - there was an awful lot of movement in the bush on the brake plate. Karol at the Slovak Klub supplies his replacement cams with a diameter of 13 millimeters which I thought was a problem until I realized what he was doing – if you drill out the brake cam bush on the brake plate, 13 millimeters is enough to take out most of the wear and you can fit new brake cams without replacing the bush, which saves a bit of time.

They work very well, although the square section is a bit oversize too - probably intentionally!

I had also noticed that whilst Karol's cams were identical, the old ones were not. You can see from the picture of the rear brake plate as the bike arrived that the position of the brake lever is a long way forward - too far forward:

The new cam puts the brake lever in a more sensible position.

FH - reassembly

 Having checked the pistons, looked at the big ends, camshaft and followers I was ready to put the barrel back in place.

First step is to Wellseal the barrel flange and stick a new gasket in place. I decided it will be easier to have the gasket on the barrel with well seal both sides before introducing the barrel to the crankcase.

Attempting to refit the barrel over the pistons revealed something interesting and that I had not spotted before - there is no lead-in chamfer on the bottom of these barrels making it very difficult to get the rings into the barrels. I used a half round file to make a chamfer of maybe 1 mm, much smaller than is commonly found on cylinders but it made all the difference.

The cylinder head went back on with Wellseal on both sides of the head gasket. I put the bolts in with Copperease and tightened them down as tightly as I could with a 12 in ratchet drive.

I've fitted and removed the rocker box several times now, and I know the optimum way to do it. Fit the gaskets to the head and apply your chosen sealant to both sides, then fit the rocker box from the front right direction remembering to trap the two exhaust push rods either side of the web in the middle of the inlet side.

I hope no one sees this as an act of wanton vandalism but I have removed one of the vestigial fins from below the rocker box, because they are an absolute pain. When they are in position, you have to put these two nuts on before the rockerbox sits down on its gaskets, because the shape of the casting means that you can't get the half nut on with rocker box fully down. One of these things was missing when I got the bike and I have just removed the other one.

I must remember to clean up that area next time the head is off.

With a bit more spannering, the head steadies are in place and the oil lines are connected. We will end this blog post here as this concludes the work on the replacement of the cylinder head.

Model A - painting more bits

 A rewarding but seemingly never ending job is painting bits for the Model A. The wheels are off and the brakes are currently in pieces and here we are with two brake arms and the torque arm for the front brake.

These are the two brake plates, with the paint cleaned off with a Scotchbrite wheel and coated with primer:

These bits had their second coat of black on the 31st of July 2026.

FH - carburation

 For the record, at the 500 mile service I have changed the carburetter slide on the FH for one with a #4 cutaway.

A #3 1/2 was previously fitted, and the plugs were quite dark.

It's still got a size 30 pilot jet, and for the record, the pilot air screw is about one quarter of a turn out. Perhaps I'll go to a size 35 pilot jet? 

Model A - chainguard

 The latest in a long line of broken bits waiting repair before they are painted is the chain guard. 

This is a pretty simple bit of welding. Initially the mounting nut is missing so I have replaced it with a new un-plated 1/4" CEI nut welded in underneath and I've filled in the worn hole as well:

The next bit is this gap which is a piece of material worn away as the chain rubs away at the chainguard. This is a bit more complicated.

First job is to chop it out with the Wiss snips and the Dremel. Next we can make a repair patch from a scrap of 18 gauge steel sheet cut to roughly the right shape, folded in the vice and refined with the linisher.

If you're careful, you can get it close enough to weld in without any filler rod which saves clean up time and reduces the heat (and hence distortion) going into the work. This wasn't one of those occasions, as I needed a bit of filler to close the gap at one end.

It's not too bad though.

Next is the other side - a bit that had been rubbing against the rear mudguard and worn a chunk away. That's it for the welding now.

With the paint finished it looks a lot better!