BSA A65 Spitfire / Spitfire Special


Make Model

BSA A65 Spitfire / Special (Mk IV)


1966 - 68


Four stroke, parallel twin cylinder, OHV, 2 valves per cylinder


654 cc / 39.9 cub in.
Bore x Stroke 75 x 74 mm
Carburetors Amal Concentric 389/206
Cooling System Air cooled
Compression Ratio 9.0:1
Lubrication Dry sump
Engine Oil SAE 20W/50
Oil Capacity 3 L / 5 pints / 0.79 US gal
Exhaust Twin


Coil, 3ET Lucas, Alternator RM19ET Lucas
Spark Plug Champion N4
Battery 12V, 10 a.h., Lucas RM19
Starting Kick start

Max Power

40.0 kW / 53 hp @ 7000 rpm
Clutch Multi-plate with heavy duty springs


4 Speed
Final Drive Chain
Gear Ratio 1st 9.30 / 2nd 6.73 / 3rd 5.07 / 4th 4.58:1
Frame Steel tubing, double cradle

Front Suspension

Telescopic forks with coil spring - hydraulically damped

Rear Suspension

Coil spring/hydraulically damped

Front Brakes

20.32 cm / 8 in., drum, twin leading shoe

Rear Brakes

17.78 cm / 7 in., drum
Wheels Steel, wire spokes
Front Rim WM2-19
Rear Rim WM2-18

Front Tyre

3.25 x 19 in.

Rear Tyre

4.00 x 18 in.


Length:  2165 mm / 85.3 in.

Height:   1117 mm / 44.0 in.

Wheelbase 1410 mm / 55.5 in.
Ground Clearance 203 mm / 8.0 in.
Seat Height 813 mm / 32 in.
Wet Weight 185 kg / 408 lbs

Fuel Capacity 

Europe:18 L / 4.8 US gal

US: 9 L / 2 US gal

Top Speed 212 km/h / 132 mph

The 1968 Mk IV version of BSA's speedy 650cc Spitfire twin was the last of the line. Two particular features distinguish it from its immediate predecessors, the first unit-construction A65 Spitfire Mk II of 1966 and the Mk III of 1967.

Firstly, the Mk II's Amal GP racing carburetors were replaced by the same maker's newly-introduced Concentric instruments on the 1967 Mk III. Secondly, the 1968 version has the twin-leading-shoe front brake introduced on BSA and Triumph 650s for that year, providing greater stopping power than the previous drum.

Less obvious technical changes for 1968 included the latest independently adjustable Lucas ignition points, providing accurate spark timing for smoother running, along with lubrication system improvements. During 1967, engine power output was boosted to more than 53 horsepower and BSA promoted its top performer in Production class racing. A factory-prepared Spitfire finished third in the 1968 750cc Production TT, behind two 750cc machines and was timed at over 132mph on a section of the Mountain course.

This Mk IV is in European trim with a large moulded fuel tank: US export models usually had a smaller tank and high-rise handlebars. Side-facing reflectors, under the front of the tank and on the rear lamp unit, were mandatory on American road machines from 1968.

Source classicbsamotorcycles.co.uk