1957 BSA A10
Pre-Unit 650 Twin

1957 BSA A10 BACKGROUND
BSA's A10 was the 650 version in it's twin cylinder heavyweight line. The 500cc version was called the A7. Following Triumph's success with its seminal 500 Speed Twin, after the war, BSA and most of the rest of the British motorcycle industry followed with their own vertical twins. BSA was first to respond in 1946 (the first year of civilian production following World War II) with the A7, Norton and Matchless followed in 1949. But by 1950, Triumph had bumped the displacement if its twin up to 650cc, and once again most of the rest of the British motorcycle industry followed suit. BSA punched the A7 out to a 650 in 1950 also, giving it the A10 name. Performance and reliability were added incrementally over several model years. As problems arose, BSA dealt with them in a slow, but steady process of development. By this time the 1957 BSA A10, the entire BSA twin line was experiencing great success in the marketplace. The 1950s truly were BSA's heyday. Good thing too, because by the 1960s, the whole thing had turned around on them, and BSA struggled throughout most of that decade until they closed their doors in 1972. Many people blame the replacement of BSA's non-unit twins, the A10 and the A7 with the unit-construction A50 and A65 in 1962 as the turning point. The timing certainly lines up.

1957 BSA A10 SPECIFICATIONS

Engine type

Displacement

Bore & Stroke

Compression

Carburetor

Primary drive

Clutch

Final drive

Gearbox

Ratios, overall:

1st, Bottom

2nd

3rd

4th, Top

Wheelbase

Seat height

Ground clearance

Brakes, front

Brakes, rear

Tires, front

Tires, rear

Fuel capacity

Curb weight

PERFORMANCE

1/4 mile

Top speed

Air-cooled OHV vertical twin

646cc

70mm X 84mm

8.0:1

1- Amal

1/2" X.305 single-row chain

Multi-plate, wet

5/8" X 3/8" chain

BSA constant-mesh 4-speed, foot shift


11.68:1

7.95:1

5.48:1

4.53:1

56.5"

32", unladen

5.5", unladen

7.0" SLS drum

7.0" SLS drum

3.25" x 19"

3.50" x 19"

4.0 gal

450 lbs


15.0 sec @ 85 mph

105 mph



MORE BSA PAGES:
BSA Motorcycles
..... BSA Gold Star
..........1939
..........1953
..........1954
..........1961
..........1962
..... BSA A7 (pre-unit 500)
..........1952
..........1955
..... BSA A10 (pre-unit 650)
..........1951
..........1954
..........1957
..........1958
..... BSA A65 (unit-construction 650)
..........1962
..........1963
..........1964
..........1965
..........1966
..........1967
..........1968
..........1969
..........1970
..........1971
..... BSA Rocket 3 (750 triple)
..........1969
..........1971
..... BSA Bantam


Check out these BSA BOOKS

BSA - THE COMPLETE STORY


BSA MOTORCYCLES: THE FINAL EVOLUTION


HISTORY OF BSA MOTORCYCLES


BSA: ILLUSTRATED MOTORCYCLE LEGENDS, by Roy Bacon


HOW TO RESTORE YOUR BSA ROCKET 3 & TRIDENT


CHILTON’S BSA MOTORCYCLE REPAIR & TUNE-UP GUIDE


BSA SINGLES 1945-1963 GOLD PORTFOLIO


BSA SINGLES 1964-1974 GOLD PORTFOLIO


BOOK OF THE BSA - OWNERS SHOP MA NUAL, PRE-WAR


BSA 350, 441 & 500 SINGLES, UNIT CONSTRUCTION 1958-1973


BSA CLASSIC MOTORCYCLES


BSA & TRIUMPH TRIPLES: GOLD PORTFOLIO 1968-1976


BSA UNIT SINGLES: COMPLETE STORY


BSA A7 & A10 TWINS, 1957-1962, by Haynes


BSA A50 & A65 TWINS: ALL MODELS


ILLUSTRATED HISTORY OF BSA MOTORCYCLES


BSA TWINS A7 & A10 1946-1962, GOLD PORTFOLIO


THE BSA GOLD STAR


MAINTENANCE MANUAL FOR BSA M20


SECOND BOOK OF THE BSA 500 & 650 TWIN 1962-1969


BSA PRE-UNIT SINGLES WORKSHOP MANUAL, by Haynes


TRIUMPH TRIDENT & BSA ROCKET 3 WORKSHOP MANUAL, by Haynes


BSA BANTAM WORKSHOP MANUAL 1948-1971, by Haynes


BSA UNIT TWINS, THE COMPLETE STORY


BOOK OF BSA SINGLES & V-TWINS 1936-1952


RUPERT RATIO UNIT SINGLE ENGINE MANUAL, BSA & TRIUMPH


RUPER RATIO, EVERYTHING BUT THE ENGINE, BSA & TRIUMPH


BSA A50 & A65 TWINS 1962-1973, Haynes Workshop Manual


BSA GOLD STAR & OTHER SINGLES, by Roy Bacon


BSA MOTORCYCLES SINCE 1950,BR>

BSA UNIT SINGLES OWNERS WORKSHOP MANUAL #127, 1958-1972, by Haynes


BSA TWINS 150 & 165 GOLD PORTFOLIO, by RM Clarke


ILLUSTRATED BSA BUYER’S GUIDE, by Roy Bacon


BSA BANTAM, by Owen Wright


BSA PRE-UNIT TWINS, by Mick Walker


BOOK OF THE BSA OHV & SV SINGLES - 250cc 1954-1970


BSA TWINS & TRIPLES, by Roy Bacon


TRIUMPH & BSA TRIPLES: THE COMPLETE STORY


BOOK OF BSA TWINS, ALL 500 & 650 1948-1962, by Floyd Clymer


BOOK OF THE BSA OHV & SV SINGLES 1945-1954: 250, 350, 500 & 600


BSA BANTAM BIBLE, ALL MODELS 1948-1971


WHERE BSAs DARE: BSA’s 1952 ISDT GOLDS & MAUDES TROPHY


ILLUSTRATED MOTORCYCLE LEGENDS: BSA, by Roy Bacon


BSA BANTAM ESSENTIAL BUYER’S GUIDE


BOOK OF THE BSA BANTAM


BSA 500 & 650 UNIT TWINS, Clymer Repair Manual


BSA COMPETITION HISTORY


BSA MOTOR CYCLING ANNUAL, 1937, Kindle






Please visit our
MOTORCYCLE BOOK STORE


Take a tour of our site...

HOME PAGE
Triumph Motorcycles
.....Bonneville
.....Tiger
.....Trophy
.....TR6
.....TR7
.....Trident
.....X-75 Hurricane
.....6T Thunderbird
.....5T Speed Twin
.....Daytona
.....Twenty-One
BSA Motorcycles
.....A65
.....A10
.....A7
.....Gold Star
.....Bantam
.....Rocket 3
Norton Motorcycles
.....Commando
.....Atlas
.....Dominator
.....Manx
Matchless-AJS Motorcycles
.....G3
.....G9
.....G12
.....G80
AMC-Associated Motor Cycles
Royal Enfield Motorcycles
.....Interceptor
.....Bullet
Ariel Motorcycles
.....Square Four
.....Red Hunter
Vincent Motorcycles
.....Black Shadow
.....Comet
Velocette Motorcycles
.....KSS
.....LE
.....MAC
.....Thruxton
Rickman Motorcycles
Japanese Motorcycles
.....Honda
.....Kawasaki
.....Suzuki
.....Yamaha
Cafe Racers
....Triumph Cafe Racers
.....Norton Cafe Racers
.....Other Cafe Racers
Choppers & Bobbers
.....Choppers
.....Triumph Choppers
.....BSA Choppers
.....Rat Bikes
Classic Racing Motorcycles

Classic Motorcycle Events
.....Auctions
.....Shows
.....Rides
Classic Motorcycle Restoration
Classic Motorcycle Shops
Classic Motorcycle Clubs
Classic Motorcycle Photo Gallery
Send us Pictures of YOUR BIKE
YOUR BIKE Pictures

HOME PAGE
.....About Us
.....Site Map
.....CONTACT US
.....Please visit our BLOG
.....Subscribe to our FREE e-zine BRIT IRON
.....BRIT IRON E-zine Back Issues

Visit our STORES
.....Motorcycle Books
.....Motorcycle Magazines
.....Motorcycle Calendars
.....Motorcycle Helmets
.....Motorcycle Rain Suits
.....Motorcycle T-Shirts
.....Whitworth Tools
.....GoPro Cameras

Crazy about cars, too? Check out our sister site:
www.American-Muscle-Cars.net

Back to top - 1957 BSA A10
Last updated 11/28/16

Learn how to BUILD YOUR OWN WEBSITE, like I did.