The Rupert Ratio BSA Unit Single Manual Vol 2

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The ultimate, multi-part manual for BSA unit-construction single-cylinder classics is nearing completion. This instalment covers absolutely everything apart from the engine…

Many moons ago, ‘Rupert Ratio’ of the BSA Owners’ Club produced an invaluable manual, an extremely detailed hands-on guide to maintaining, rebuilding and trouble-shooting the Unit Single engine. That extensive and informative book became the must-have accessory for all owners of late Beesa singles and is widely accepted as THE work of reference for all the models, C15, B25, B40, B44, B50 and even their very close relative, the Triumph TR25W.

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There was only one problem.

The first book only covered the unit single engine and none of the cycle or chassis parts, so if you needed any technical advice about anything other than the motor then you had to resort to other, less detailed sources of information.

Now that situation has been remedied with this new publication, another extensive practical handbook which examines the single-cylinder BSAs from tip to tail-light. It’s no surprise that this book took a little while to put together – author Dave Smith (Rupert Ratio’s alter-ego) must have burned plenty of midnight oil trying to condense his experience as the BSAOC’s long-standing technical officer into 335 densely-packed pages.

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BSA Singles on Now…

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The well-illustrated and comprehensive chapters cover everything from correctly identifying your machine, through brakes, hub, wheels, forks, chains, exhausts, filters, electrics and instruments. Dave Smith relies heavily on his three decades of experience with these bikes and has avoided simply regurgitating chunks of other manuals and publications – instead you get his personal experience and advice about which methods, components and techniques have proved successful over the years. He’s also included chunks of invaluable technical data from original factory records.

Almost every single page contains a carefully captioned image – and many of the black-and-white photos are of components as they appear now, 40 years old and frequently a bit battered. This is deliberately done to reassure owners that their parts are not the only ones which might be a bit wonky! Images like the ones showing five different types of fork yokes or two alternative kinds of gear lever are incredibly helpful to the restorer, especially if your project arrived as a pile of separate parts and you’re not certain exactly which ones really belong with your bike…

Chris Golby, RC reader and editor of the BSAOC’s magazine, is extremely impressed with the manual:

‘Having read it, I can only conclude that it does what it says on the tin and loads more! It really does cover everything. I was amazed at the fantastic level of detail. Not only does it map the history of changes and when various parts were introduced, superseded and/or deleted but it identifies the correct finishes even down to the colours and type of paint used.

‘Turn the pages and see the different types of frames, wheels and other main components used; then turn the pages further to find the rest, right down to the smallest components like petrol taps, speedo drives, etc. They really are all there, along with the models and years they were fitted, what are the weak points to watch out for, what breaks and how to fix it and with very useful tips for renovation and improvement. This applies to virtually every part in the manual.

‘Not only is this a must for all owners of Unit Singles but it’s also a great bedtime read for owners of other BSAs as well.’


‘The Rupert Ratio Unit Single Manual: Volume 2, Everything But The Engine’ is published by Panther Publishing Ltd, ISBN 9781909213142 and costs £22.95 from or

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