VELOCETTE MAC
You might imagine that every farmhouse, henhouse, outhouse and doghouse in existence must surely have been emptied by now – but no. Still more old motorcycles emerge from the depths of neglect so that people like Stuart Francis can rebuild them..
You might imagine that every farmhouse, henhouse, outhouse and doghouse in existence must surely have been emptied by now – but no. Still more old motorcycles emerge from the depths of neglect so that people like Stuart Francis can rebuild them…
The story starts in 2014 when Mossy, a local character with an eerie ability to unearth old motorcycles, told me and my friend Donald about a stash of ‘barn find’ motorcycles that the owner wanted to sell. To whet our appetites he had a couple of photographs of the machines. I call them photographs, but they looked like they were taken at the bottom of a disused coal mine with a box Brownie using a failing torch for illumination. Even so, Donald and I were sufficiently interested to quickly arrange the 10 hour trip across New Zealand’s South Island before anybody else stepped in. I was particularly interested in the near-complete 1938 Velocette MAC which the owner said was virtually ready to run.
We arrived at the appointed time to find the owner wasn’t there but would be back in five minutes. He turned up two hours later. The place was a boat repair yard, car customisation yard, scrapyard and rather disorganised. After squeezing our way into the dark recesses of the boat repair shed we were shown into a large unlit store room where the machines were located. Half an hour later we had some lights and found a treasure trove of machines ripe for rebuilding or restoration. I bought the Velocette, a 1924 L24 BSA and a 1915 Douglas, Donald bought a 1918 BSA and a 1924 Douglas CW. After spending half an hour cutting a path through dense undergrowth around the back of the boat shed, we were finally able to extract the machines and load them onto our trailer.
In case you’re unfamiliar with Veloce’s range of ohv single-cylinder roadsters, the first M-series Velocette, the 250cc MOV, was introduced in 1933 and this sophisticated, well-engineered machine sold well. Velocette quickly introduced the 350cc MAC which continued in production, relatively unchanged, until 1951, when a new aluminium cylinder head and barrel were introduced. The alloy MAC continued in production with a swinging arm frame, telescopic forks and a new gearbox until 1960. The 500cc MSS was introduced in 1935, housed in the stronger KSS frame, and it continued to 1948. An updated MSS was introduced in 1954 with a swinging arm frame and a new aluminium cylinder head and barrel, continuing until 1969.
Back to my MAC. A week later I finally got the Velocette up on the work bench and had a really good look at what I’d bought. It was at this point I started to have doubts. The heavyweight girder forks were only loosely assembled, the steering column was back to front, the lower frame was a casting like the military model and the frame number had a different suffix to what I expected. I did check the engine number in the gloom of the storeroom, but now realised what I thought was a 3 and 2 were actually an 8 and 7. After a bit of head scratching and detective work, I found out I had a 1946 MAC, one of a batch shipped to NZ just before Velocette introduced Dowty forks.
My next step was to check over the engine and gearbox. Turning the engine over showed little compression and it made a slight clicking noise. Checking for a spark produced an anaemic glimmer which appeared occasionally. Hoping for better from the gearbox, I could only find three gears and a clutch that did not seem to want to separate.
I had already decided that this was going to be a rebuild, not a restoration, retaining as much patina of the bike’s age as I could. The first thing I tackled was the lack of compression. Removing the rocker covers revealed the reason: the inlet valve was partially stuck open and the clicking noise was the pushrod that had jumped off of its rocker end. A light tap with a drift and the valve snapped back in to place.
I then decided to whip off the head, redo the valve seats, ream out the valve guides and check the inlet pushrod for damage. I was pleasantly surprised with the state of the head, with only a tiny bit of rust in the inlet guide, the probable cause of the sticky valve and an indication that the machine had been standing for a long time. The inlet port had been polished and opened out slightly. The pushrod was also in good condition with just a couple of small witness marks.
The cylinder bore was in reasonable condition, but the earlier type barrel, with less finning, had a number of damaged and cracked fins. Fortunately I had a later barrel in the pile of spares that came with the bike. After a quick hone and a new piston it looked good. A quick check for end float and big end wear indicated the bottom end was OK.
The next job was the magneto. Taking off the timing cover, I noticed that one of the screws was only held by gasket goo. Velocette magnetos have to be on top form to get a good starting spark as the low geared kickstarter only turns the engine over at about half of the speed of most other machines. A good clean up then re-- magnetising followed by replacing the pickup and re-setting produced a very healthy, slow speed spark. The magneto was run on my homemade test bench for an hour to make sure everything was OK. The loose timing cover screw was a bit of a pain. The lug it screwed into had split but a repair with plastic metal soon had it fixed.
The gearbox was a bit of a mystery. Everything seemed to be in the right place with perhaps a touch too much end play. However the gear shaft bearing retaining cup and nut on the end of the gear shaft were missing. A careful rebuild, getting the end float just right and making a bearing retaining cup, produced all four gears and a smooth gearchange. The clutch was another matter altogether: broken springs, badly repaired clutch plate drive dogs, friction inserts missing and home-made clutch