The Matchless G3

Though perhaps BSA’s B31 overshadows it as Britain’s ubiquitous and most beloved 350, the Matchless G3 was made for longer than the Small Heath favourite, while the Matchy also boasted sterling war service, another string the Beesa didn’t have to its bow.

The G3 (with 69 x 93mm bore and stroke, giving 348cc) made its debut in the 1935 model line-up, alongside the G80; the duo were to appear alongside each other until 1966, with the engines recognisably developed from that first, pre-Second World war introduction. In the early days there was a 250cc variant too, the G2, plus a sporty 500, the G90, latterly joined by a racier 350cc model, the G4. But these were all relatively short-lived, while it was the G3 alone which saw war service, as something like 80,000 were supplied to the allied war effort, in both G3 and G3L; ‘L’ for lightweight, on account of the AMC Teledraulic forks. The L, in particular, was a forces’ favourite.

Post Second World War, it was the G3 (as well as the AJS equivalent, the Model 16) which spearheaded AMC’s civilian range, the 350cc models joined by 500c versions (G80 and Model 18). Spring frames came (denoted by an S, while there were Candlestick, Jampot and then Girling suspension units) plus there were C for Competition versions too.

The 1950s G3 swapped to an alternator in 1958, in 1959 the S letter was dropped, then in 1962 came a revised bore and stroke (to 74 x 81mm, later changed to 72 x 85.5mm) and the short-lived name Maestro, with the last incarnation of machines, from 1964 to 1966, having Norton Roadholder forks and Norton wheels. But, until the end, the engine was still recognisably G3.

was purchased from Armours and the finned clamp at the cylinder head came from Russell Motors. The Altette hooter was sent to Lynn Isaac for a full overhaul and restoration and supply of a mounting bracket. Unfortunately, Lynn had a stroke and won’t be doing any more repairs, but his son found my hooter and returned it.

While trying up the rear mudguard in the frame, preparatory to painting, it became obvious that the combined stay/lifting handle was not correct. I took photographs and dimensions from my friend Tony Saunders’ G3 and made one.

The original Bowden combination clutch and brake levers came with the bike. They had the worn pivot holes in the clamps rebushed, new pivot bolts made, and new S/S OBA fixing screws fitted before they were taken to be replated at Prestige Electroplaters in November 2019. They were ready to collect in January 2020, looking really good; they were promptly reassembled and readied to fit. Failing to locate any suitable one inch handlebars, I had a pair made in stainless to the same pattern as Velocette ’bars that I have found to be very comfortable.

A parcel was received from Russell Motors containing all of the studs, bolts, nuts, washers and spacers necessary to fasten the two parts of the frame together and to install the engine and gearbox. This, I decided, was a better option than grubbing through the box of assorted dirty bolts etc to try and identify the necessary parts.

In preparation for the wheels being rebuilt, I turned my attention to the hubs. I stripped out the bearings and spindle from the rear hub and discovered that the spindle, which should have been a sliding fit in the hollow spindle, was seized beyond removal. The bearings had already been stripped out of the front hub when I bought the bike and a second hollow spindle and bearings appeared to be new. I bought a new rear hollow spindle with bearings, seals, cups, plain washers and reassembled the hubs. They were taken to Steve Lomas to built into the rims and have new tyres fitted and were returned in March 2020, ready to fit.

But with various other projects on the go, I was getting nowhere fast and struck upon an idea and asked if my friend Dan Spokes would undertake the reassembly. Dan takes up the story…

“Around the middle of September 2020, Rob asked me if I would be interested in helping him put a 1939 G3 Matchless together; a daft question, of course I would, in fact I would be more than happy to help. He told me it was in a lot of bits, but he’d had a lot of the work done insofar as getting parts overhauled, painted etc. Most of the big lumps were there, albeit in the many boxes that, on Monday, September 21, 2020, arrived at my garage/ workshop courtesy of Rob and his van.

“Along with the parts were various workshop manuals and a very vague parts book, so the next few days found me sifting through boxes, familiarising myself with the bits and pieces and giving the books a good looking at, though, on reflection, these books and manuals were pretty poor and lacking in good information. Anyway, off we went. I started to loosely piece together some of the obvious bits and the motorcycle started to take shape.

“The flywheels were checked and trued by Rob and the main bearings were replaced. The crankcases were bolted together and installed in the frame. The

overhauled Burman gearbox was slipped in to place along with the reconditioned girder forks and the newly rebuilt front and rear wheels. By the end of October we had a rolling chassis.

“The rest of the engine assembly was easy enough. The barrel was honed, a new piston and rings were fitted along with new valves and guides in the cylinder head, plus new rocker shafts and arms were duly fitted in the rocker box. Anyone who has ever rebuilt a pre-war G3 will know that the dynamo has to be slotted in to place before the primary cases and clutch can go on – an awkward arrangement. This done, things were looking good. One of the fiddliest jobs for me at this point of assembly was the fitting of the magneto and its platform. What a performance. My fingers either not long enough or too fat. But, hey, I’m sure there must be an easy way of fitting the mag. But for the life of me, I couldn’t find it… Eventually though, I coped.

“Over the next couple of months, the machine started to look like a proper motorcycle and a very nice one indeed. Valve and ignition timing was sorted, primary and rear chains fitted. Mudguards on, handlebars, cables grips, all now in place. During this time, Rob had managed to make a combined rear stay and lifting handle that fitted nicely, plus one or two other things that I’d asked him to do. A prop stand bolt. A rear wheel spacer. A speedo cable. He’d also sorted out the saddle, which he believed to be the original, and which was duly installed.

“By early January 2021, with the bike nearing completion, I turned my attention to the wiring.

Looking through the various Matchless workshop manuals I had at my disposal, and looking at the various wiring diagrams, it became clear that the light switch that was part of the replica headlight was not shown in any of the diagrams that I had in front of me, also I had to incorporate a stop light and switch plus a combined horn and headlight dip switch, none of which were shown in any of the prewar diagrams. So I’d sit down, have a cup of tea, and work it out…”

In May 2021, I brought the bike home with Dan’s, with a few small jobs to finish.

I had not paid sufficient attention to the condition of the rear chainguard before it was painted and a bow had prevented Dan from fitting it. I bought an Indian made one that still wouldn’t fit. Investigation revealed that, typical for Matchless, there were changes resulting in parts that are similar but not the same. This was the case for the spacers for the rear wheel spindle. With the correct spacer, the chain alignment came good and it became possible, after a modification, to also fit the painted original rear chainguard.

The process was assisted by Matchless’ excellent practice of making the main section of the mudguard quickly detachable and leaving the short section in situ. With the guard completely out of the way, the problem became easy to see.

With this resolved and some slight attention to the adjustment to the front wheel tape rollers – another area where Matchless make a simple proposition complicated, it was time to consider starting the bike.

Despite the magneto being fully overhauled, it emitted no spark. It dawned upon me that the combination of painted engine plates and magneto platform had robbed it of an earth. Not being sure how the factory resolved this, I made an earth strap to connect a mounting stud to the chaincase rear cover. Spark restored, the engine started promptly, returned oil to the tank after an agonising wait and ran very sweetly. Everything worked.

A road test in the Lincolnshire Wolds proved the bike to be a delight. Mechanically sweet, smooth, first-class transmission, good brakes and a good riding position make it a very well-mannered bike to ride. I’m very pleased with it – it was worth all of Dan’s hard work and frustration. Well done and thanks to him.