Useful data

Engine bore 82 mm
Engine stroke M20 94 mm
Engine stroke M21 112 mm
Petrol tank capacity 3 gallons
Oil tank capacity 5 pints
Gearbox capacity 1 pint
Inlet tappet clearance (cold) 0,010 in
Exhaust tappet (cold)  0,012 in
Compression M20 4,9:1
Compression M21 5:1
Tyres 3,25/3,50-19
Piston ring gap 0,008-0,012 in
Piston clearance 0,0035-0,0055 in
Ignition timing 7/16 in BTDC
Magneto point gap 0,012 in
Spark plug gap

0,012-0,018 in