My 1966 BSA Bantam D7 Super Restoration



Technical Data

Engine Number on top of crankcase below cylinder.

Frame Number at top of steering head tube.


Capacity 174 c.c.

Cylinder bore 61·5 mm.

Stroke 58mm

Compression ratio 7·4—1

Piston ring gap minimum·009 in, maximum·013 in.

Number of piston rings = 3.

Sparking plug Champion L7

Plug points gap minimum·020 in, maximum·025 in.

Contact breaker points gap ·015 in.


Gear ratios top 6·58, second 9·26, first 17·4

Clutch friction plates 3

Teeth on: engine sprocket 17

Gearbox sprocket 16

Clutch sprocket 38

Rear chainwheel 47


Fuel tank 2 gallons

Gearbox 3/4 pint

Front forks 1/8 pint each


Tyre size front 3·00—18, rear 3·00—18

Tyre pressure front 17 psi, rear 22 psi

Brake size dia 5½ in, wide 1 in.


Bore 7/8 in.

Main jet 140

Pilot jet 25

Throttle valve 375/3½

Needle position 2

Needle jet ·1055

General Details

Overall length 793/8 in

Wheelbase 511/8 in

Ground clearance 5½ in.

Seat height 31 in.

Overall height 36 in.

Handlebar width 27¾ in.

Tyre Pressures

The recommended tyre pressures are based on a rider’s weight of 140

lbs. If the rider is heavier, increase the pressures as follows: —

Front tyre: Add one lb. Per sq. in. for every 28 lb. Increase above

140 lb.

Rear tyre: Add one lb. Per sq. in. for every 14 lb. Increase above

140 lb.

If additional load is carried in the form of a pillion passenger or

luggage, the actual load bearing upon each tyre should be determined

and the pressures increased in accordance with the Dunlop Load and

Pressure Schedule.


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