WELCOME to my blog about restoring vintage overhead camshaft AJS and Velocette 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 sent all of my cammy AJSs to Bonhams last year and they were sold at the Autumn Stafford Sale. 

The URL of "vintageajs" for this blog is now somewhat misleading but it's too late to change it and there is still plenty to read about the AJAY projects. If you happen to be the new owner of one of the bikes that I recently sold then there is plenty here to read about its build. I still have 2 early Big Ports waiting in the wings ....but they will have to wait until I've completed the Velos. 

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. 

A lot of work has been done on these bikes over the past 3 years and the INDEX PAGE provides links in chronological order of these projecst so far.

In August last year I acquired a DOHC 250 Velo Engine. I have completed the rebuild of this engine and the dry build of this bike is also finished. Details of this project can be found in the links in the INDEX page.

I also acquired the engine, exhaust pipe and petrol tank of KTT 581 early last year. This bike has an interesting and somewhat sad history. I have rebuilt the engine and plan to put this in a bike when I have completed the existing 3 Velos - full details of the project so far in the links here.

I have now started on the final builds - painting, plating, chemical blacking and powder coating of the 2 KTTs and the DOHC 250. The first bike, KTT 305, is finished (just waiting for the exhaust pipes to come back from chroming) and the 2nd bike, the DOHC 250, is currently being built.

A digression from the current bike projects - a 130mph supercharged MG Midget back in 1935....

Really!!? More here.

During the last 5 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 owned 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 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. 

This bike is now in the Sammy Miller Museum.

 

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

and this was completed in March 2023.

 

The Index Page for this project can be found here.

I also reported briefly 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.

Supercharging pre-WW2 MG Midgets – 130 MPH!

 

A slight digression from the current bike projects….

I was recently thumbing through an ancient copy – June 1935 - of The Motor

when I came across 2 adverts relating to MGs of the period - I take an interest in these because I have one. The first of these was from MG itself advertising the MG Midget and its racing prowess

and the second was from Zoller superchargers, again advertising the speed that could be obtained from an MG Midget by supercharging.

What caught my eye was the fact that both adverts are claiming over 130 mph (209 km/h), presumably the same car and event. With a 750cc engine this will almost certainly have been a J4. I am not an expert on the different variants of MG Midgets so I have to resort to Wikipedia which tells me:

“The J4 was a pure racing version with lightweight body work and the J3 engine, but using more boost from the supercharger to obtain 72 bhp (54 kW).”

Just for the record, the “8 H.P.” referred to in the Zoller advert is not a measure of the actual power of the engine but rather a value assigned for purposes of taxation based loosely on the size of the engine – see here for details.

As anyone that has read my blog in the past will know, I also put a supercharger - a Marshall blower - on my MG PA some years ago (see here and here) which is why these articles caught my eye. The claimed power of 72 bhp is substantially more than the 42.6 bhp that we measured on the dyno after fitting and setting up the blower on my car; admittedly, I am running with around 3 – 4 psi maximum boost pressure rather than the much higher boost that these early midgets would have been using. Incidentally, the J4 engine only has a 2-bearing crankshaft whereas the PA that I have with 847cc has a 3-bearing crank.

However, 130 mph! Assuming this is not a complete fabrication (and the magazine is dated June 4 1935, so it’s not an “April Fool”), I cannot imagine being in one of these little cars at a speed even approaching this sort of figure. This is my little MG PA at a classic car event at Amberley earlier this year

and this is my installation of the Marshall compared to the Zoller in a PA.

I find that driving my little car at 55mph (on 4-inch-wide tyres) is quite exciting enough - they were brave men back in 1935!

Nevertheless, after 5+ years of driving with the blower fitted I have found it to be totally reliable and a great performance booster - especially for improved torque at lower engine speeds. Barry Walker still has these kits for sale for anyone interested.