1957 BSA C12
My Dad bought this bike in the 1970s, perhaps as late as the 80s, to get his motorcycle license on. He rode it for a while, managing to kill the primary gear because the seller told him to run it dry (he replaced it and the gear vendor gave him an oil specification to use, and it’s been on the same primary gear since) and then eventually parked it up at my Grandparents’ place in Inverloch, Victoria (where all old mechanical equipment in our extended family went to die) after upgrading to a 750.
When my Grandfather retired, he began restoring several of the old vehicles laying around, including this bike. He for some reason painted it the Maroon color it is today, and faithfully restored as much as he could, including doing the leather upholstery himself. Unfortunately either his cheapness or lack of finances shows, because many of the chrome parts are simply painted silver and the electrical system was in a shambles.
My grandfather passed away in 2007, and my father reclaimed the bike since it was originally his. It sat in Dad’s shed with very little attention - apparently a cork seal in the fuel petcock valve meant that fuel simply leaked out of the tank almost as fast as you could put it in, so they never got it running.
We brought it to my place in 2015, where I began the process of re-restoring it. It had 1303 miles on the clock when I got it, however I don’t believe that to be correct - my father certainly put more than 1300 miles on it, and bought it used, but we don’t believe anyone put enough miles on it to clock it over 100,000. It’s possible Grandad was forced to replace the speedometer at some point, or he may have cracked it open to fix it and in the process reset it.
My grandfather registered it as a 1954 C11, but I am almost certain it’s actually a 1957 C12. I thought at first that perhaps it had had a transplanted engine into a 1954 frame. It’s engine number is BC11G36266, the frame number being EC1212172. According to the BritBike website for dating 1950s BSAs, 1957’s engine numbers started at 33009, with 1958’s starting at 40001, and the frame numbers for 1957 starting at 8998 and finishing at 16000. Note the “EC12” in front of the frame number, further suggesting it’s not a C11.
This puts both sets of numbers squarely in the range for 1957, I am not yet sure how that will work if I am fortunate enough to get it running and then go to register it with VicRoads.
These bikes are actually worth very little these days, mostly due to their ubiquity - the value of this bike to us is almost entirely sentimental.
- Pick up, clean up and assess - Complete, Dec 2015
- Change engine oil - Complete, Dec 2015
- Check oil pump function - Complete, Dec 2015
- Check valve lash - Complete, Jan 2016
- Replace ignition coil - Complete, Jan 2016
- Replace wiring, regulator and rectifier - Complete, Jan 2016
- Fix speedometer - Complete, Feb 2016
- Fix horrible slack in primary drive chain - Complete, Mar 2016
- Rewire headlight and tail light, replace bulbs - Complete, Mar 2016
- Adjust clutch cable - Complete, Mar 2016
- Fuses (important!)
- Fix fuel leaks
- Replace air filter element
- Change primary drive oil
- New 12v battery
- Replace hand grip with standard, non terrible one
- Replace suspension bushes in rear end, likely front forks need a service as well.
- Replace broken spoke, possibly replace tires as well
Documentation, Manuals and Service Sheets
Spark Plug: Champion L78, NGK #B7HS
Ignition Coil (Original): Lucas 6V #47275
Carburettor: Amal Monobloc #375⁄25
Main Jet: Amal #105
Headlight: Lucas #312 (6v 35w) or #325 (12v 38w), #414 (12v 50w) - British “Pre-focus” aka P36D (?).
Tail light: BAY15d (12v, 21/5w).
- BSA Sheet #404 - Engine service without dismantling [PDF]
- BSA Sheet #405 - Engine dismantling and decarbonisation [PDF]
- BSA Sheet #408 - Gearbox [PDF]
- BSA Sheet #411 - Clutch [PDF]
- BSA Sheet #412 - Hub dismantling (ignore suspension section, C12 is swinging arm not plunger) [PDF]
- BSA Sheet #603 - Engine lubrication system [PDF]
- BSA Sheet #708 - Carburettor - Monobloc type [PDF]
- BSA Sheet #808 - Electrical System (808D is the relevant sheet to C12) [PDF]
- Lucas Workshop Manual - Alternators RM13, RM14, RM13/15, RM15, 5AF [PDF]
- Lucas Workshop Manual - Electric Horns HF1234, 1235 [PDF]