Friday 5 July 2024

WELCOME to my blog about restoring (mainly) vintage overhead camshaft AJS motorcycles

Apologies to anyone that has come to this page expecting to see exclusively vintage AJS motorcycles .....scroll down the page a bit and you will find plenty of them. However, I ran out of AJSs to restore and I'm now working on early cammy Velocettes.

In 2023 I started the restoration of 2 early Velocette KTTs plus another Mk 1 OHC cammy special - a few details about each of these bikes can be found here and here

Quite a lot of work has been done on these bikes over the past 14 months and the INDEX PAGE provides links in chronological order of the project so far.

I now have 3 rolling chassis up together - see here - and I'm now working on many smaller details - seats, tanks, steering dampers and steering locks etc. More details of the latest work on the project here

I also came across a lady by the name of Florence Blenkiron - a remarkable lady that, among other things, was riding an OHC AJS  back in 1933.

Acknowledgement to whoever owns copyright of this picture

This bike would have come out of the AJS factory at the same time as my 33/7. I put in a couple more links to her past at the end of my latest post.

During the last 4 years I have posted quite a lot of information and to aid navigation the "Labels" section on the right side of this page lists the various projects.

The labels marked "INDEX" give a link to a page that provides a complete list and links to all of the separate sub-projects related to that main project.

Alternatively, scroll down this page and see what's here...

When I started this blog I already owned (and still own) a 500cc AJS R10

that I've been riding for many years and wanted an early 350cc bike. I bought one at a Bonhams auction; this is what I brought home....

....a bit of work was needed to bring it to back to life 

Full details of the restoration can be found here.

During the restoration of the K7 I figured that I could put an early overhead camshaft Velocette cylinder, cylinder head and cambox onto the crankcases of an AJS 350cc engine from 1931, convert it to chain-driven OHC and make an engine that looks like a K7 but has a Velocette top-end. I had a 1928 350cc AJS sidevalve that I had bought on eBay and used that to create the AJcette credit to both manufacturers.

It looks pretty similar to the K7 and to demonstrate that there really are 2 bikes, here they are both together.

Details of the AJcette project can be found here.

I have quite a lot of early Mk1 OHC Velocette parts and after completing the AJcette I decided to use some of these to make a replica of a one-off bike that AJS built in 1929/1930 for an attempt on the world speed record. The original is a huge V-Twin beast that started out with a naturally-aspirated engine but, having failed to gain the record, was supercharged ...and again failed. The bike ended up in Tasmania for many years and, after being repatriated to the UK and restored, it is now in the National Motorcycle Museum.

This is what the original looked like:

and this is my recreation.



Like the AJcette, the V-Twin uses Mk 1 OHC Velocette cylinder components. The full story of how this bike was built can be found in the links here.

There is also a 14 minute edited Youtube summary of how these bikes came about here and a longer unedited version here.

In January 2022 I started the restoration of a 1933 AJS Trophy Model

and I have just completed (March 2023) this bike:


The Index Page for this project can be found here.

I also reported on a couple of my other projects ....vintage OHV Nortons

 and putting a Marshall supercharger onto my 1934 MG PA


I hope you find something of interest.

Tool Boxes, Steering Locks more Casting Patterns and another Steering Damper

I had fitted new Andre steering dampers to both KTTs but was missing a damper to fit to the cammy special. I had this collection of bits and pieces.

One of the most important parts is the base of the damper – the bit that fits inside the stem of the bottom yoke that supports the entire assembly and I was missing one of those, at least, one that fitted. Rather than make one from a solid piece of steel (which would generate a lot of swarf) I made it in 2 parts

and then silver soldered them together. I have retained the original tapered locking bolt which, importantly, has a small pin that engages with the slot that I machined with a small end-mill in the base to avoid the bolt rotating when it’s tightened.

There were a few more little bits and pieces to make, shown below.

The long hexagon nut serves 2 roles: it locks the base to the steering stem with a 3/8” BSF thread whilst the other half of the nut is threaded 3/8” BSCY (which is a finer thread) into which the stud attached to the damper knob is screwed. Finally, a dome nut (will be plated later) has been made to lock the knob onto the stud and a new star spring (the Banbury Run autojumble) completes the assembly.


Mark Barker makes the most beautifully crafted toolboxes (the AJS 33/7 has one of his) and he has made me 2 that will be fitted to both KTTs which I also picked up at the autojumble.

These are not yet fitted but this is how one looks just resting in the frame tubes

and which will be fixed in place in due course using stainless steel U-bolts.

These are available in a variety of different sizes, one of which fits the frame tube exactly.

Top Tube Saddle Clip (KA-111)

The front of the seat is supported by one of these and I had  ...none. This is what it looks like in the parts book

I asked in my last blog post and also in Fishtail (Velo club magazine) if anyone had one that I could use to make a casting pattern – and now I have one. This is what it looks like in the flesh.

This one is showing its age – some brazing repair on the top part and some distortion on the bottom; nevertheless, it is quite adequate as a basis for making patterns.

I have described in some detail how I make resin casting patterns using original parts, see for example here and here so only a brief description is given below.

Various gaps and holes are filled in with wood (the large hole is filled with a piece of wood cut from a broken garden fork handle, machined to the correct diameter and cut in half to fit), body filler and thick gasket paper is added to the surfaces that will be machined on the castings to ensure there is an allowance for shrinkage.

Each of these is then suspended (in this case, using a magnet) in a small plywood box and surrounded by screws. All surfaces are liberally coated with Vaseline

before pouring silicone rubber
halfway up the parts.

After attaching conical pieces of glossy paper to each

silicone is poured to the bottom of the screws to form the top half of the mould.

The mould can now be dissassembled and used for making resin copies. This is what they look like after setting and removing the top half of the mould

and, after a bit of a cleanup, these are the finished items - 2 of each.

In addition to these resin patterns, I have also modified an existing cylinder head steady clamp (KA-43) by adding a ½” diameter boss.

This will be used as part of a steering lock assembly – see below. All these patterns are now with the foundry for casting.


Steering Lock

After fitting the petrol tanks, it was immediately apparent that steering locks were required to avoid damage to the tanks from the handlebars/clamps. It would be a pity to put a dent in these beautifully crafted tanks before they had even been painted!

To this end, I used a piece of square section solid aluminium

that I had left over from some other job to make these

and that, together with some round rubber buffers from eBay (40mm OD, 10mm ID, 20mm thick) and a head steady clamp

makes an effective steering lock.

I have modified the design slightly from the picture shown above by incorporating a boss, which will be threaded 5/16” BSF, into the KA-43 part of the clamp and so eliminating the nut and washer on the inside but I have to wait until the castings come back from the foundry to include this.


And Finally…..

I have been out and about on the AJS 33/7 Trophy recently and a buddy of mine drew my attention to a lady by the name of Florence Blenkiron. In particular, he noticed that the bike that she is riding here

Acknowledgement to whoever owns copyright of this picture

is a 1930s cammy AJS – this is the racing version rather than the off-roader that I have (see here and here). This picture was taken in 1933 so would have come out of the factory the same time as mine. To say that Florence Blenkiron was an achiever would be a serious understatement – she was the first woman to break the 100-mile per hour barrier on a motorcycle at Brooklands among other things. More details can be found on Florence here and here.

Tuesday 11 June 2024

Completion of the Rolling Chassis (nearly)

I can see that it’s nearly 7 weeks since I last posted anything and anyone following the saga of the restoration of the 3 Mk 1 Cammy Velos could be forgiven for thinking that I had given up. Far from it! Apart from doing a bit in the garden and looking after grandchildren from time to time I have been working solidly in the workshop on making and fitting various cycle parts to the rolling chassis.

The pictures below show the current status of the bikes.

Specifically, I have completed fitting of the mudguards, sourced and fitted footrests, made numerous parts for the rear brakes and fitted the petrol tanks and steering dampers. I should mention again that the crankcases being used are simply to add structural rigidity (these are actually spare crankcases left over from the engines that I used for the AJcette and AJS V-Twin projects) and the gearboxes have been added to check chain alignment.



The frames on these early cammys were made reasonably accurately and I decided that the rear mudguard that I had fitted onto KTT 305 would end up on the cammy special and that I would reproduce the longer mudguard and additional horizontal stay that is depicted in a 1931 KTT promotional picture, below,

Acknowledgement to Ivan Rhodes “Velocette, Passion of a Lifetime”, page 62.

and is apparent on Dave Brewsters bike – KTT 305 - at the TT in 1931.

Acknowledgement to Dennis Quinlan

Interestingly, Ivan states in his book that there is no evidence that such as machine (as shown in the promotional picture) ever existed. However, Dave Brewsters bike, which was despatched directly from the factory to the Isle of Man, looks remarkably similar.

And so KTT 305 now looks like this:

Front stands/lower mudguard supports, part number FS-1/2K, were needed for both KTT 55 and the cammy special. For these, “ends” were machined

to form the cross-piece of the stand

before silver-soldering 2 lengths of ½” diameter tube with swaged ends to bolt to the bottom of the forks.

Fitting of the mudguards on the 3 bikes is now complete and time to turn attention to footrests.



I had only one of pair of correct Velocette footrests and rather than start a mini project to replicate these by making castings I decided to adapt Norton footrest hangers. The starting point are WD (War Department) footrests that were produced as spare parts for WW2 Nortons and for which some guy in Australia must have bought a pallet load plus in an ex-WD sale. They are advertised on Ebay and I have used these in the past for the AJS V-Twin.

They take a couple of weeks to come from Australia and they look like this when they arrive.

Perfectly preserved wrapped in grease.

After cleaning up they look like this

and after unscrewing the footpeg part, straightening the hanger with oxy-acetylene, making new ½” square footpegs that screw into the hanger (7/16” BSCY), spark-eroding a 7/16” square hole to fit the KTT’s square footrest support bar (FK-23) and removing the serrations on the milling machine they look like this.

The orientation of the square hole in the hanger is important for the position of the footrest.

The last step is to make the square bars and spacers. The picture below shows one complete set of footrest parts, including spacers, for one of the KTTs.

There are a couple of aspects of tooling that are very useful in making these parts. The first is a collet chuck for the lathe with square collets to be able to hold the square bar

and the second is a series of long drills to drill the long spacers.

The long spacer is 7.5” in length and although it would be straightforward to simply turn it around and drill in 2 operations it is more convenient to be able to drill it in one go.


Brake Bits and Pieces

Lots of little pieces are required to set up the rear brakes; in no particular order, wing nuts (KS-44) for adjustment, swivel joint for brake pedal (7/16” OD and threaded - FK-43), trunnion for brake rod (½” OD and ¼” clearance hole - FK-43/2), brake rod (SL-30/12), rear brake rod spring (KS-43) plus, of course, the brake pedal itself (F-39/2) and its support (F-130/3).  I had already sorted out pedals and their supports (see here) so it was now time to make all the little bits.

I have never tried making a wing nut ….and don’t plan to. I ended up buying half a dozen beautifully made brass wing nuts with a ¼” BSF thread and then extending them with a short piece of solid brass

and clamped together

before silver soldering into one, continuing the 1/4" BSF thread through the added portion and milling a cylindrical section on the end to engage with the trunnion.

Machining the other small parts for the rear brake is straightforward and I took advantage of the machine/tooling setup to also make a swivel joint (W26) for the front brake. I do not plan on using a rod for the front brake but rather a cable and the swivel joint has been made to fit the nipple that I will eventually use for a 2mm wire cable.

This requires a bit more effort as the swivel needs 2 different diameters and a slot, machined with a small (2.5mm) end mill, through which to insert the cable.

The entire collection of bits is shown below.


The KTT brake rods require a kink as the pedal and operating arm are not in alignment.

Petrol Tanks

As I’ve mentioned a number of times in the past, I have had numerous tanks made in India and rather than repeat a previous posting I refer the reader to here. It was now time to use the 3 petrol tanks that were made many years ago in the back streets of Bangalore to see if they actually fitted!

I had only unwrapped one of them since bringing them back to the UK and I found this scrap of newspaper inside one of the other tanks

which dates their time of manufacture pretty accurately.

Using the long rubber buffers (FK-151/KTT) from the Velo Owners Club and 5/16” BSW bolts all the tanks fitted perfectly. I will, in due course, make 12x shouldered bolts (FK-152) but that can wait until I have a bit of spare time (!!) in the workshop.


Knee Grips  

I had bought 3 sets of knee grips (KA-72) some years ago

and it was now time to fit them. Each of these is squeezed around a plate (KA-80/2) that is attached to the tank with 2x ¼” threaded studs …but I didn’t have any plates, not even one to copy, and so it was time to reverse engineer one using one of the knee grips itself.

The first step is to coat the knee grip with grease and press this onto a piece of cardboard.

Although not perfectly defined, this is sufficient to be able to “fill in the gaps” and cut it out to make sure it fits perfectly into the hollow part of the knee grip.

This shape then needs extending by approximately 3/8” all round the periphery to produce a good tight fit on the rubber. This is done freehand, “by eye”, and that shape is then transferred to a piece of 18-gauge sheet metal

which is cut out with a disc-cutter and cleaned up with a flap disc before hand finishing with a file.

The plate is fixed to the tank studs through 2 holes which need to be positioned to give the correct orientation of the knee grip on the tank. What is the correct position? I have looked at many period pictures of early KTTs and it seems that there is no one single orientation and it could be that top riders positioned these individually to suit their riding position. The picture below of Alec Bennett with Percy Goodman in 1928 is typical

Acknowledgement to Ivan Rhodes “Velocette, Passion of a Lifetime”, page 23.

and I have used this as a guide to fit my plates/knee grips.

….and 5 more plates later

all bikes are now fitted with tanks and knee grips.

Interestingly, the depiction of these parts in the Velocette Parts List (which, I have to admit, I did not look at until after I had made my plates) has interesting positioning of the plate fixing holes.


Steering Dampers

Some years ago, I acquired a brand new, boxed Andre steering damper.

complete with fitting instructions.

I can’t remember what I paid for it but it was substantially more than the 1 guinea (21 /-) stated on the instructions.

The fixing is clearly intended for a flat-tanker and it can be dated pretty accurately from the fact that the instructions indicate a Model P Triumph. These bikes were produced from 1925-1926 and so I would estimate the steering damper to be close to 100 years old. How it survived all this time complete with its box is a miracle.

Anyway, it was never intended to be a museum piece and it is now fitted to KTT 305.

whilst another one that I found, also never used, is fitted to KTT 55

There is some simple bracketry yet to be made to anchor the dampers to their respective tanks and another damper yet-to-be-found to fit to the cammy special.

There has been quite a lot of work over the past weeks that I haven’t reported in detail simply because it is not very interesting. For example, the footrests and KTT footrest support stays (FK-167) for the 3 bikes required a total of 15 spacers (6 each for the KTTs and 3 for the cammy special); making one spacer is not interesting but making 15 is downright boring! But it takes time….  

There is a still some fettling to be done on the work that I have just reported – shortening the front mudguard by 1 ½” on KTT 55, fitting the brake pedal to the cammy special and there are still some cycle parts yet to be fitted - seats and bump-seats, oil tanks, controls etc… but at least I now have something that is starting to resemble 3 motorcycles.

On the issue of seats, I am missing one part, namely a Top Tube Saddle Clip (part number KA-111). The parts list shows it to look like this:

If anyone has one of these (both parts of the clamp) that I could borrow for a couple of weeks to make moulds for casting patterns I would be most appreciative. If you do have one and are willing to lend it then please contact me at I will pay postage costs etc.. Thanks.


And Finally….  although these projects are a long way from completion – I haven’t even started on engines and gearboxes yet – I have started preparations for the next 2 early cammy Velos, both early flat-tank Model Ks.

One of these was fitted with a lighting set. I don’t often put lights on bikes but in this instance, I would like to retain the period feature of a Lucas MDB1 magdyno (see here) and the lighting set that was fitted to the bike when I received it.

When I mentioned to Paul at APL Magnetos that I would like it refurbished he was less than enthusiastic (that is an understatement!!) because these magdynos are poorly designed and can give problems even when perfectly rebuilt.

Anyway, he's taken it on and was in need of a cam ring for another magneto rebuild – this is what he had.

These are actually quite straightforward to make. Firstly, a blank is made on the lathe that has the correct OD and the smaller of the IDs (ie with the points open) and this is then set up in the dividing head on the milling machine

to remove material over a ~600 segment for the “points closed” part.

The various slots for the advance/retard will be put in after their position has been accurately determined with respect to the magnets/armature in the magneto.