Identification Marks.

Engine number and Prefix letters MAC : Stamped on left-hand side of crankcase below the cylinder base flange. (Always include serial letters when quoting the identification number.) See Fig. 7.
Frame Number : Prefix letters RS. Stamped on right-hand side of saddle front mounting lug.
Gearbox Number : Prefix No. 11/ or 14/. Stamped on right-hand side of housing at top.

Engine.

Capacity (Swept Volume) : 349 cubic centimetres. 21.289 cubic. in.
Bore and stroke : 68 m.m. x 96 m.m. 2.677 x 3.779-in.
Actual Bore diameter : 2.677-in.

 

Tappet clearance (Cold). For running. Inlet .005-in.
  Exhaust .005-in.
Tappet clearance (Cold). For setting timing. Inlet .030-in. to
  Exhaust .035-in.

Note.-Follow instructions on page 26 before checking or resetting tappet clearances.

Ignition Timing. 38 ° before top dead centre, fully advanced (Points open .0015-in.)

Valve Timing. (When checked with .030-in. to .035-in. Tappet clearances.)

Note.-Readjust to running clearances after checking.

  

Cam
marked

Cam
marked

Cam
marked

  

M17/5

M17/4

M17/7

Inlet opens 30° 50° 19° Before top dead centre.
Inlet closes 60° 60° 49° After bottom dead centre.
Exhaust opens 60° 70° 49° Before bottom dead centre.
Exhaust closes 30° 40° 19° After top dead centre.

Compression ratio : 6.75 to one.
Compression space : 60-62 c.c.

Valve spring free length  Outer : 2 9/64 (2.1406) inches.
   Inner : 1 15/16 (1.9375) inches.

 

Piston Rings.

End gap-Compression rings : .0085-in. to .0115-in. 

Stocked 

.020-in.

.040-in

.060-in

oversize

End gap. Oil control ring : .0105 to .0135-in.
Side clearance : Compression rings : .0005 to .0025-in.
Side clearance. Oil control ring : .0025 to .0045-in.

 

Valves. Seat angle 45°

Gudgeon-pin. .624-in. diameter (± .0001-in.) Stocked .001-in. oversize.

Small end bush. .625-in. inside diameter ( +.0005-in. - .0002-in.)

Big end. Crankpin roller track diameter 1.374-in. 16 rollers-caged. 3/16-in. diameter by 9/16-in. long. Stocked .0002-in. and .0004-in. oversize.

Carburetter.

Amal. Type 276EY /1AT. 15/16-in. choke diameter.
  Throttle valve. 6/4.
  Needle jet size 107 (No. 4/061).
  Main jet 130.
  Jet needle position 3.
Monobloc. Type 376/48.
  Throttle valve 3½. 
   Needle jet 105.
   Main jet 200.
   Pilot jet 25.
   Needle position 3.

Magneto. Lucas type K1F. Anti-clockwise rotation. Fixed ignition with automatic advance and retard unit type JY16A.

Dynamo. Miller type DVR. 6-volt. Anti-clockwise rotation with automatic voltage regulation.

Lighting Bulbs. Head lamp : 24-W x 24W 6-volt S.B.C. Cap. or 30 X 24W Double Filament Bifocal Pre-focussed type.

Parking : 6-volt, 3w. S.C.C. Cap. or 6-volt, 3W. M.E.S. Cap.

Tail : 6-volt, 6W. S.C.C. Cap.

Stoplight : 6-volt, 18 x 6W. Offset pin Stoplight type.

Battery. 6-volt. 13 A.H. Varley, Exide, or Lucas.

Gearbox. 4-speed. Foot controlled.

Ratios (overall) with 21 tooth final drive sprocket : First, 14 to 1 ; Second, 9.6 to 1 ; Third, 7.3 to 1 ; Fourth (top) 5.5 to 1.

Sprockets. ½-in. pitch x .305-in.

Engine 21 teeth. Clutch, 44 teeth. Final drive, 21 teeth. Rear wheel, 55 teeth.

Chains.

Primary. ½-in. pitch. .305-in. width. .335-in. roller diameter. 67 pitches.

Rear. ½-in. pitch. .305-in. width. .335-in. roller diameter. 124 pitches.

Wheels. Rims : Front, WM2 x 19-in. Rear, WM2 x 19-in.

Spokes :

Front—Brake side. 61-in. x 10 SWG. 18 off.

Front—Left side. 71-in. x 10 SWG. 18 off.

Rear —Brake side. 71-in. X 8 /10 SWG. 20 off.

Rear —Right side. 71-in. x 8 /10 SWG. 20 off.

Tyres. Front, 19-in. X 3.25-in. Rear, 19-in. X 3.25-in.

Tyre Pressures. Minimum solo : Front, 16 lbs. per sq. in. (1.1 atm.) Rear; 18 lbs. per sq. in. (1.2 atm.)

For pressure chart see page 85.

Capacities.

Petrol tank : 3 Imperial gallons. 3.6 U.S. gallons. 13.6 litres.

Oil tank :½ Imperial gallon. .6 U.S. gallon. 2.27 litres.

Gearbox :½ Imperial Pint. .6 U.S. Pint. .28 litres.

Front fork : 1 Imperial Pint. .15 U.S. pint. 71 cu. cent. per strut.

Sparking Plug.

14 m.m. diameter. 18 m.m. (extra long) reach.

Suitable types : KLG FE70. Champion NAB. Lodge HLN.

Dimensions.

Wheel base (In normal loaded position)  53¾-in. - 136.5-cms 
 Ground clearance (In normal loaded position) 5½-in. - 14-cms.
 Saddle height (In normal loaded position) 30½-in. - 77.5-cms.
Overall width 27.1-in. - 70-cms.
Overall length 7 feet - 213-cms.
Weight unladen. 355-lbs. - 161 kgs.


Recommended Lubricants

 

B.P.

Duckhams

Mobiloil

Shell

Wakefield

Engine : Summer (Ambient temperatures above 60° Fahrenheit)

Visco-Static*
or

Energol ' 40 '

Q20/50*

or

NOL ' Forty '

Mobiloil Special*

or

Mobiloil B.B.

X100 10W/30*

or

X100 40

Castrol XXL

Engine : Winter (Ambient temperature below 60° Fahreheit)

Visco-Static*
or

Energol ' 30 '

Q20/50*

or

NOL ' Thirty '

Mobiloil Special*

or

Mobiloil A

X100 10W/30*

or

X100 30

Castrol XL

Gearbox

Energol ' 40 '

NOL ' Forty '

Mobiloil B.B.

X100 40

Castrol XXL

Front Fork

Energol ' 20 '

NOL ' Twenty '

Mobiloil Arctic

.X100 20/20W

Castrolite

Wheel Hubs

Energrease C3

H.B.B. Grease

Mobil MP

Retinax A

or

Retinax H

Castrolease
' Heavy '

Primary Chain

Energol 40

NOL ' Forty '

Mobiloil B.B.

X100 40

Castrol XXL

Rear Chain

Energrease C3G

Laminoid

Mobil MP

Retinax A

or

Retinax H

Castrolease Graphited

For Grease Gun

Energrease C3

H.P.G. Grease

Mobil MP

Retinax A

Or

Retinax H

Castrolease
Medium

For Oil Can

Energol 10

NOL ' Ten '

Mobil Handy Oil

Donax A.1

' Oilit '