Reviving a 1924 BSA L24 3½ HP
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 were for sale. The 10-hour drive north from Invercargill to Kaikoura was well worth it. I bought a 1946 Velocette MAC, a 1924 L24 BSA and a 1915 Douglas, Donald bought a 1918 BSA and a 1924 Douglas CW.
After sorting out the 1946 MAC Velocette I turned my attention to what had been sold as a 1926 L26 3½ HP* (350cc) side-valve BSA. I decided to try and keep as much of the patina as possible. By far the biggest problem was that the back wheel was missing, as were the exhaust pipe and magneto, and the rear mudguard was also damaged and twisted. Fortunately it came with a load of second hand parts, 3 engines, a refurbished barrel with a new piston, 4 gearboxes, a couple of clutches and some other spares. The engine was quite an easy job. After removing the rather tired top end I found the bottom end was not too bad; fitting the refurbished barrel and piston got the project off to a flying start. What did take time was making the cylinder head valve covers and sealing rings. Having machined a piece of brass to the right shape, screw-cutting the fine thread on my worn lathe was a bit fiddly. Silver soldering a piece of bored out hexagon brass bar onto the top of the valve cover finished them off. The sealing rings were just very thin pieces of aluminium tube that I annealed to soften them up. The gearbox was next and after replacing the output shaft ball bearing and a rather worn gear selector, it all seemed to go together quite well. A suitable old Lucas magneto was found in my stock of spares and a quick rebuild, including re-magnetising, produced a healthy spark. The badly twisted rear mudguard was held together by the number plate mounting bracket. It took a lot of work to tease it straight, weld up the cracks, tap out the larger dents and paint it in an industrial semi matt black that looks like old worn enamel. The rear carrier looked all right until it was removed, but some deft work with the welder and grinder, followed by clamping it in the big vice and applying pressure through a piece of timber soon sorted it out. The front forks were stripped down to check for wear and were acceptable. BSA used an unusual arrangement, the side links have short tubes brazed onto them that run in bushes in the steering head arms and fork legs. By far the biggest job was fabricating the rear wheel; a narrow 19 inch, WM1 rim – a wheel from my pile of bits seemed a good start. It had to be re-spoked with a different offset and a dished rear sprocket manufactured. After a bit of trial and error and a quick skim in the lathe, it all started to line up and did not look out of place. Originally the 1924 L24 had dummy rim brakes at both ends but at some point the front brake was replaced with the slightly later internal expanding band brake. The spring steel brake band is anchored at one end and the brake lever pushes the other end, expanding the band and forcing the friction material onto the inside of the brake drum. The friction material was rather worn, so after some initial discussions about bonding, a local friction material supplier riveted on a new lining. The rear brake is an early BSA Bantam item that does not
By far the biggest job was fabricating the rear wheel; a narrow 19 inch, WM1 rim – a wheel from my pile of bits seemed a good start.
look out of place. The exhaust pipe was an old Matchless G80 pipe that was severely cut and shut to fit the tortuous path it had to follow, leaving it outside in the rain to rust added to the look. The petrol tank was ok but petrol shot out of the AMAC carburettor when the fuel was turned on. Some tedious work with needle files has improved things no end but it still gets slightly damp at the joint.
The initial attempts to start the machine were very frustrating, tantalising occasional glimmers of ignition convinced me that success was just around the corner, it wasn’t! The problem became clear, some of the oil from the leaking oil tank had got into the magneto. After cleaning out the magneto and further lowering the fuel level she would start and run reasonably well. My first attempt at riding the machine was not the best experience I had ever had. The recovered oversize bicycle saddle was very uncomfortable, however the real concern was the gear change. It was very difficult to engage first and nigh on impossible to change gear when the clutch was pulled in, Suspicion fell on the gearbox mainshaft end float so I rotated the main shaft slowly and found lots of end float, then carried on rotating and it disappeared. It turned out the large flat-faced engagement dogs on the gears were touching and masking the true end float. A thicker thrust washer soon sorted it out. I was exchanging e-mails with Rick Parkington (an expert on these mid 1920s BSAs) about the gearbox problem, when he pointed out that the machine was probably a 1924 model. He sited the frame number, petrol tank construction, rear carrier construction and the lack of a damper on the front forks, as good indicators that it was an earlier machine. The L24 was BSA’s cooking 350cc side- valve but it had a 3 speed gearbox, clutch and kickstarter, it was relatively easy to operate and maintain (the handbook suggests setting tappet gaps with a business card). In 1924 it would have had beaded edge wheels, changing over to wired rims in 1926/27. It is worth reflecting how far machines had come in the previous 10 years, when direct belt drive was still common and most machines had to be push started.
So what is it like to ride? A good tickle on the carburettor, slightly retarding the ignition followed by a couple of hefty swings usually brings it chuffing into life. The clutch is quite light and first gear is quite low so I quickly change up to second whilst juggling the throttle, air lever and gear lever which are all on the right-hand side. Picking up speed slowly I slip it into third and like a stately galleon it cruises along at about 30mph. With the wide bent back handlebars the riding position is rather upright. Slowing down takes a bit of time and coordination. The front (expanding band) brake is rather weak, it may improve a bit when the new lining beds down. The Bantam rear brake is reasonably effective and is the brake I rely upon. However at some point you have to change down, I leave this as late as possible as it involves closing the throttle and air lever and letting go of the front brake to move the gear change lever, all with the right hand. I have tried clutch-less gear-changes with the left hand but with little success. So the key question is, was it worth the effort? I can only respond with a resounding ‘yes’. Once you get used to its foibles, it is a real blast to ride on country roads, and the technical challenges only add to the enjoyment. I must admit I wouldn’t want to do much town riding given the slow acceleration and poor brakes but that aside I usually finish up with a big cheesy grin on my face whilst riding it. The only outstanding niggle is I have broken two kick start springs so far and finding a replacement is difficult.
Postscript: I was recently coerced by local photographer David Russell (Southern Exposures) into helping with a photo shoot for a family antiviolence campaign poster. He wanted an old motorcycle for a ‘steampunk’** lady to pose on, the 1924 BSA L24 fitted the bill. The lady arrived one Sunday afternoon dressed up in her “steam punk” outfit, complete with a hard leather corset which her partner then proceeded to tighten up. She got on the bike with some difficulty due to the tight corset. I did ask whether she would like to ride the bike but her experience was limited to modern machines, hand change, lever throttle machines with virtually no brakes can be a bit of a challenge. *The RAC horsepower tax rating based on piston area. ** ‘Steampunk’ is a homage movement to vintage fashion.
3 ½ horsepower, waiting to be unleashed.
TOP LEFT Stuart prepares to test his work. ABOVE Steampunk comes to Invercargill. LEFT The refurbished top end with new home made valvecaps and AMAC carb.