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. 

I spent the first few months of this project sorting out the front and rear hubs to get the wheelbuilding underway, making patterns for a variety of smaller components and working on the girder forks. Castings for smaller components came back from the foundry and have been machined.

More recently, I embarked on a project to make Mk 1 KTT cambox scavenge oil pumps. The entire project is described in these links: part 1, part2 and part 3.

The pumps were finished a few weeks ago and I have since been working on getting rolling chassis for all 3 bikes completed and fitting mudguards. There is quite a lot of work in making the mudguard stays for 3 bikes. One set is finished - details here

and I'm now working on the other 2 bikes.

During the last couple of 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 ....giving 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.

Fitting Mudguards …and a workshop accident

Fitting mudguards is not a particularly exciting topic but nevertheless an important task that if done carelessly can really spoil the appearance of a bike. In particular, mudguards of the correct shape and diameter should be fitted to give a constant or near constant distance between the mudguard and the tyre (although I recognize that this is not possible on swinging arm bikes where the relationship between the wheel and mudguard changes with the suspension and the rear mudguard needs to allow for wheel removal), and although it may be stating the obvious, the guard needs to be fitted to be exactly on centre with the tyre.

I get my mudguards in raw steel from Renovation Spares and with 21” x 3.00” tyres fitted to the bike, I use 29” x 4” and 30” x 4 ½” D-section guards on the front and rear respectively.

which then need to be cut to length and fitted. Simon, who runs Renovation Spares, has also put in 3/8” indents in both sides of the front mudguards to avoid interference with the girder forks.

Before any mudguard fitting takes place, it is important to check that the rebuilt wheels are on-centre and, for the rear wheel, that the chain alignment is correct. For this, it is necessary to put the gearbox back in the bike temporarily.

A new IWIS ½” x 5/16” chain is fitted. All OK here.

I have used ½” diameter thick wall (1.5mm) tubing for making both front and rear stays on all my recent projects and as far as I am aware this was how KTT 55 would have left the factory in 1929, as suggested by period pictures of Mk 1 KTTs and the brochure picture below.

However, the period picture of KTT 305 in the Isle of Man with Dave Brewster on board in 1931 (and the factory records indicate that the bike was sent directly from the factory to the IoM) clearly shows flat stays on the front.

Further digging has revealed the following from Ivan Rhodes book Technical Excellence Exemplified:

On Page 26 Ivan states that Works Velocettes left the factory with flat alloy mudguard stays at the front - that would explain the above picture.

There is another difference between the Dave Brewster picture and other contemporary KTT pictures and that is the existence of an additional horizontal stay to support the rear mudguard. The 1931 brochure picture, shown below,

 Acknowledgement to Ivan Rhodes Technical Excellence Exemplified

clearly shows a horizontal stay.

I will therefore try and recreate exactly what is shown in the IoM picture except that I will use steel rather than aluminium flat bar for the front stays because it is much easier to work.

I have used 20mm x 3mm flat strip for the upper stay and 25mm x 3mm strip for the lower stay. These bend nicely around an appropriately sized piece of round bar

 

and then, with some heat from oxy-acetylene, bent to follow the edges of the mudguard

using an off-cut screwed to a piece of wood.

This really needs 3 hands – one to hold the gas torch and the other two to hold the metal bar. For many years I have adopted the practice of sandwiching the torch between my left arm and my body to give 2 free hands for working the metal. This is not a safe practice and the dangers of this were brought home when making this bracket as I managed to pass the flame over my right thumb. Oxy-acetylene works well for bringing metal up to red heat quickly because, at over 3000 ⁰C, it is the hottest flame available in the workshop …but it can really do some damage to flesh and skin!

After 2 weeks the wound is healing nicely but I shall be more careful in the future to avoid barbecuing parts of my body.

The front mudguard turned out OK.

Stays for the rear mudguard are made using ½” diameter thick wall tubing as I mentioned earlier. Although I have a bender for this diameter of tubing the radius of the bender is too small to give a proper fit around the outside of the mudguard. However, in the many offcuts of round bar that I have there was one that was a good fit for the mudguard and the tubing can be bent by hand without using a tube bender, as shown below. These are 1m lengths of tube and so there is plenty of leverage.

After shaping and cutting to length, the press tool that I had previously made for the 33/7Trophy project

was used to swage the ends. The first pressing is done in the vice

but this can’t provide enough pressure to close the end

and the 20-ton hydraulic press (using typically 6 – 8 tons pressure) is used to finish the job.

After drilling and rounding the ends

the upright stay is finished.

The part of the stay with the handle for hauling it onto the stand has a short straight section at the top and this needs bends of a smaller radius. These are done using the tube bender

before fitting to the bike and setting up for tack welding to the first upright stay.

The last part of this stay is the cross piece that connects to the mudguard.

Before tack welding this piece, the mudguard is clamped to the upright stay to ensure it is in the correct position when the attaching lugs have been made and fitted.

The lugs are made from 16mm x 3mm flat and are shaped

and bolted to the mudguard before tack welding with TIG.

….being careful not to weld the screw head to the lug!

After removing the stay to complete the welds, mudguard fitting for one bike is finished.

 

The frames were made sufficiently accurately 90 years ago that the mudguards and stays made for one are interchangeable with the others and I will use the rear guard and stays shown in the above picture for the cammy special.

Anyway, 2 more bikes to go….