Re­viv­ing a 1924 BSA L24 3½ HP

Old Bike Australasia - - OUT’N’ABOUT - Story Stu­art Fran­cis

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.

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