1962 BSA A65

1962 BSA A65 - NEW UNIT TWIN
After 15 years of great success with their pre-unit twins, the 500cc A7 and the 650cc A10, BSA had a real challenge ahead of them. How do you follow up a 'home run' like the A7 & A10? They had proven themselves to be not only strong, but reliable (BSA's hallmark) with success on the racetrack and in the showroom. The pre-unit BSA twins were widely regarded as the epitome of the classic British vertical twin at the time. By 1957, Triumph MotorcyclesTriumph had converted its 350cc 3T to a unit-construction, followed by the 500cc twins in 1959. BSA being the parent company to Triumph must have felt a pressing need to beat Triumph to the punch with its big twins. Triumph was due to convert the 650 twins over to unit construction for model year 1963. So BSA made sure they introduced their new unit-construction 500 and 650 twins a year ahead of them, with the 1962 BSA A65 and A50.
ABOVE: Unfortunately, no suitable photos were available of a 1962 BSA A65. So this 1962 BSA A50, which is the 500cc version & almost identical in every other aspect, stands in. The most visual difference is that the A50 had a 7-inch front brake & the 1962 BSA A65 had an 8-incher. If you have a '62 A65, please send pictures of your bike.
ABOVE: BSA unit-construction A65 engine. This one is out of a '66 A65 Lightning (note the dual carbs). The engines remained essentially the same, externally from 1962 through the end in about 1972.

1962 BSA A65
THE BASIC LAYOUT

In a classic British move, BSA Motorcycles elected to build both their new 500cc A50 & their 650cc A65 to be basically identical in almost every way. This was done in an effort to save the costs of tooling & manufacturing different sets of components. So, aside from minor cosmetic variances, the only parts that weren't in common on the two bikes were the front brake (the A65 had an 8" SLS & the A50 had a 7") & the top end. Both models shared the same 74mm stroke, with a bore of 65.5mm for the A50 (yielding a displacement of 499cc), & 75mm for the A65 (for 654cc), slightly oversquare (very slightly, it was actually almost "square"), very unusual for a Brit bike at that time. Going Unit Construction not only cleaned up the lines of the bike, but it dropped 40 pounds off the weight. The new 1962 BSA A65 in single carb form made 38hp at 5800rpm with a compression ratio of 7.5:1. The engine followed the traditional British vertical twin layout: 360-degree crank (pistons rising & falling together), timing gears on the right, primary drive on the left & it followed BSA tradition by placing the camshaft behind the cylinders & running the pushrods up through a tunnel in the cylinder block. With the new unit design they tried so hard to 'clean it up' that they robbed it of much of its visual character. Whereas the old pre-unit BSA twins were handsome engines, the new A50s & A65s looked like bland lumps, the same on all sides. This was actually part of a clever plan BSA had hatched to be ahead of the rest of the world in adopting the "power egg-look". Why an engine should be made to look like an egg is beyond me, but this is the kind of thinking that ruined BSA in the years to follow.

1962 BSA A65 - NEW ENGINE
The conversion to Unit Construction, started with 1962 BSA A65 & it's A50 little brother, allowed BSA to make many other needed (and some not so welcome) changes. For instance, the rocker arms were now on shafts supported by lugs cast into the cylinder head, rather than in separate rocker boxes which were bolted to the head. It made for a much stiffer structure & because all the valve gear was contained in a cavity in the very top of the head & sealed by a one-piece aluminum cover, there were virtually no top end oil leaks. A very neat package, in this respect.
1962 BSA A65 - TEETHING PROBLEMS
In an effort to save a few cents (farthings), clever BSA used a copper-lead bushing instead of a main bearing on the timing side. These quickly wore out & caused lots of problems, and since the crankshaft received its oil supply from this location, the resulting lubrication problems caused engine catastrophic engine failures. It would be a few years before BSA would get it right. Today, if you have one of these early Unit BSA Twins, you can retrofit an upgrade to a roller bearing, if it hasn't been done already.

1962 BSA A65 - NEW FRAME & CYCLE GEAR
For the 1962 BSA A65, a new full double-crade frame was designed following the pattern of the previous A-Range machines. Partially welded, partially brazed lugs, it was heavily reinforced around the steering head & swing arm pivot, making for a very solid frame.


1962 BSA A65 SPECIFICATIONS


A65 Star Twin

A65 Royal Star

Engine type

Displacement

Bore & Stroke

Compression

Carburetor(s)

Ignition

Engine output

Primary drive

Clutch

Gearbox

Ratios, overall:

1st, bottom

2nd

3rd

4th, top

Final drive

Frame type

Wheelbase

Seat height

Ground clearance

Suspension, front

Suspension, rear

Brake, front

Brake, rear

Tire, front

Tire,rear

Fuel Capacity

Curb weight

Standard Roadster

Premium Roadster

Air-cooled OHV vertical twin

654cc

75mm X 74mm

9.0:1

1- Amal Monobloc, 1-1/8"

Breakers & coils, Lucas

38 bhp @ 5800 rpm

Triplex chain

Multi-plate, wet

4-speed constant-mesh, right-foot shift


11.0:1

7.18:1

5.13:1

4.35:1

Chain

Welded & brazed lug, full double cradle

54"

33"

7"

Telescopic fork, hydraulic damping

Swing arm, 2 Girling dampers

8"SLS drum

7" SLS drum

3.25" X 18" Dunlop

3.50" X 18" Dunlop

2.4 gal (US models); 4.8 gal (UK & export)

406 lbs

A WORK IN PROGRESS
In our efforts to complete our online index, and make this the world's greatest website about classic British motorcycles, we're building pages as fast as we can. The first thing we add are the pictures. Then come the specifications and then the history. So, if you see a page that just has only pictures on it, or just pictures and specs, please check back in a few weeks to see if we have it done. Thanks for your patience. And thanks for visiting Classic-British-Motorcycles.com. Please tell your friends about us.


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


HISTORY OF BSA MOTORCYCLES


GOLD STAR BUYERS COMPANION, 5th ED.


BSA PRE-UNIT TWINS


THE BSA GOLD STAR: MOTORCYCLE HISTORY


BSA PRE-UNIT TWINS


BSA MOTORCYCLES: THE FINAL EVOLUTION


BSA SINGLES RESTORATION, BY ROY BACON


BUILDING BUDGET BRITS: REFURBISHING BSA & TRIUMPH TWINS


BSA: ILLUSTRATED MOTORCYCLE LEGENDS BY ROY BACON


BSA UNIT SINGLES WORKSHOP MANUAL BY HAYNES


ILLUSTRATED HISTORY OF BSA MOTORCYCLES BY ROY BACON


BSA & TRIIUMPH TRIPLES: GOLD PORTFOLIO


BSA SINGLES 1964-1974 GOLD PORTFOLIO


BSA A50 & A65 TWINS 1962-1973 SHOP MANUAL BY HAYNES


BSA 500 & 650 TWINS: ESSENTIAL BUYER’S GUIDE


TUNE YOUR BEEZA BSA A10


BSA A7 & A10 TWINS, 1947-1962 SHOP MANUAL BY HAYNES


BSA UNIT SINGLES: THE COMPLETE STORY


BSA TWINS A50 & A65 GOLD PORTFOLIO


BOOK OF OHV & SV BSA SINGLES 1945-1954


BOOK OF OHV & SV BSA SINGLES 1954-1970


THE GOLD STAR BUYER’S COMPANION


BOOK OF THE BSA: SHOP MANUAL FOR PRE-WAR BSAs


BSA UNIT CONSTRUCTION SINGLES


MAINTENANCE MANUAL FOR THE BSA M20


HOW TO RESTORE YOUR BSA ROCKET III/TRIUMPH TRIDENT


BSA PRE-UNIT SINGLES SHOP MANUAL, 1954-1961 BY HAYNES


BSA TWINS A7 & A10 GOLD PORTFOLIO


BSA SINGLES 1945-1963 GOLD PORTOLIO


BSA TWIN RESTORATION BY ROY BACON


BSA UNIT TWINS


BSA BANTAM SHOP MANUAL, 1948-1971 BY HAYNES


BSA A50/A65 TWINS: ALL MODELS BY ROY BACON


BSA GOLD STAR & OTHER SINGLES BY ROY BACON


BSA BANTAM OWNERS MANUAL


BSA: CLASSIC MOTORCYCLES


CHILTON’S BSA MOTORCYCLE MAINTENANCE MANUAL


CLYMER’S SECOND BOOK OF BSA 500 & 650 TWINS, 1962-1969


RUPERT RATIO BSA UNIT SINGLE ENGINE MANUAL


BSA BANTAM BIBLE, 1948-1971


BSA BANTAM


BOOK OF THE BSA, ALL SINGLES & V-TWINS 1936-1952


BSA M20/21 SUPER PROFILE


BSA MOTORCYCLES 1935-1940


BSA ROCKET 3 & TRIUMPH TRIDENT 1968-1976 BY ROY BACON


BSA MOTORCYCLES SINCE 1950


BSA MOTORCYCLING ANNUAL 1937


1971-72 BSA 250-500 OWNERS MANUAL


1967 BSA BANTAM D1/D3/D5 OWNERS MANUAL


BSA TWINS & TRIPLES BY ROY BACON


HAYNES 1954-1961 BSA PRE-UNIT SINGLES SHOP MANUAL


BOOK OF BSA 500 & 650 TWINS 1948-1962 BY CLYMER


BSA: THE SCRAPBOOK SERIES


BSA BANTAM: THE ESSENTIAL BUYERS GUIDE


HAYNES 1947-1962 BSA A7 & A10 OWNERS SERVICE MANUAL BY HAYNES


BSA REPLACEMENT PARTS LIST 1971 BSA A75 ROCKET 3


BSA REPLACEMENT PARTS LIST 1968 BSA A75 ROCKET 3


BSA INSTRUCTION MANUAL: MODEL D10 BANTAM


BOOK OF THE BSA BANTAM


BSA GOLD STAR: PORTRAIT OF A MOTORCYCLING LEGEND


BSA COMPETITION HISTORY


BSA GOLD STAR SUPER PROFILE


HAYNES 1958-1972 BSA SINGLES OWNERS SERVICE MANUAL


TRIUMPH & BSA TRIPLES: THE COMPLETE STORY OF THE TRIDENT & ROCKET 3


BSA MOTORCYCLE CATALOG 1929


1949 BSA BROCHURE: WORLDS LARGEST MOTORCYCLE MANUFACTURER


BSA BANTAM, ALL MODELS BY ROY BACON


BSA GOLD STAR: MOTORCYCLE HISTORY


BSA PRE-UNIT SINGLES, B, C & M RANGES 1937-1963 BY ROY BACON


BSA UNIT SINGLES C15 TO B50, 1958-1973


BSA A7 & A10 TWINS, ALL MODELS 1946-1963 BY ROY BACON


BSA A50 & A65 TWINS, ALL MODELS 1962-1972 BY ROY BACON


ILLUSTRATED BSA BUYERS GUIDE BY ROY BACON


BSA FACTORY SERVICE SHEETS FOR THE 1950s


BSA BANTAM OWNERS POCKET BOOK


TRIUMPH TRIDENT & BSA ROCKET 3 SHOP MANUAL






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