Technical Data
Identification Markings
(To be quoted when ordering spares or requesting Service information)
| Engine Number* | (Prefix VR, VM or MSS). Stamped on crankcase at left-hand side below cylinder base. (Scramblers have suffix 'S'.) |
|
Frame Number* |
(Prefix RS). Stamped on right-hand side of seat front mounting lug. (Scramblers have suffix 'S' or /35.) |
| Gearbox Number* | (Prefix 12- or 14-). Stamped on top of gearbox housing on right-hand side. (T.T. close ratio boxes have suffix 'R'.) |
| * The prefix letters or numbers identify the type and must always be quoted. The serial number alone is insufficient. | |
Engine Dimensions
| Thruxton, Venom, Scrambler and MSS | Viper 350 Scrambler | |||
| Cylinder capacity (swept volume) : | 499 c.c. | 30.45 cu. in. | 349 c.c. | 31.39 cu. in. |
| Cylinder bore : | 86 mm. | 3.3878 | 72 mm. | 2.8362-in. |
| Stroke : | 86 mm. | 3.385-in. | 86 mm. | 3.3858-in. |
Tappet Clearances.§ (Set cold).
| Running clearance* | Inlet .006-in. | Exhaust .008-in. |
| For checking timing | Inlet .053-in. | Exhaust .052-in. |
| §See page 25 before checking or adjusting. | ||
| *For Scrambler clearances see page 96. Thruxton model see supplement | ||
Valve Timing. When checked with tappet clearances of .053° inlet, and .052° exhaust.
| Cam M17 /8, Venom and Viper from En. No. VR1262 and Scrambler, | |
| Inlet opens | 45° before top dead centre. |
| Inlet closes | 55° after bottom dead centre. |
| Exhaust opens | 65° before bottom dead centre. |
| Exhaust closes | 35° after top dead centre. |
| Cam M17 /7, MSS and Viper to En. No. VR1261 | |
| Inlet opens | 19° before top dead centre. |
| Inlet closes | 49° after bottom dead centre. |
| Exhaust opens | 49° before bottom dead centre. |
| Exhaust closes | 19° after top dead centre. |
Compression Ratios.
| MSS | 6.8 to one (86 to 88 c.c.). |
| Venom | 8 to one (68 to 69 c.c.). |
| Viper | 8.5 to one (47 to 48 c.c.). |
| 350 Scrambler and Viper Clubman | 9.3. to 1 (42 c.c.). |
| 500 Scrambler and Venom Clubman | 8.75 to 1 (64-65 c.c.). |
Sparking Plug
14 m.m. dia. 18 m.m. (extra long) reach.
| Suitable types for MSS : | Champion NA8 ; KLG FE80 ; Lodge HLN. |
| For Venom and Viper : | Champion NA10: KLG FE100: Lodge 3HLN. See also page 71. |
Piston Rings.
| MSS. | Venom. | Viper. |
Scrambler 500. & Venon Clubman |
|
| Compression rings : | .015-in. | .015-in. | .010-in | .020-in. |
| Oil control ring : | .015-in. | .010-in. | .012-in | .020-in. |
| Side clearances are : | Compression Rings | .001-in. to .003-in. |
| Oil Control Rings | .0027-in. to .0047-in. | |
| Details for the 350 c.c. Scrambler and Viper Clubman are as for the Viper. | ||
Valves.
Seat angle 45°
| Gudgeon Pin. | .8235-in. diameter. (+.0001-in.) (—.0001-in.) |
Small end Bush. .8245-in. diameter. (+.0005-in.) (—.0002-ins.)
|
Big End. |
Crankpin roller track diameter, 1.499-in. Crankpin rollers, 3/16-in.+ 9/16-in. 18 off, caged, single row. Rollers stocked .0002-in. and .0004-in. oversize. |
Carburetters.
Monobloc or Concentric type 8° downdraught. Early Clubman and Scrambler models were fitted with the Amal l0TT9 type.
| Clubman models and Scramblers use Amal 10.TT.9 | ||||||
|
Model. |
MSS. |
Viper. |
Viper. |
Venom. Venom. |
Venom |
|
|
Type |
376 /49 |
376 /56 |
376 /61 |
389 /14 |
389 /15 |
R930/29 |
|
Size |
1 1/16-in. |
1-in. |
1 1/16-in. |
1 1/8-in. |
1 3/16-in. |
1 3/16-in |
|
Main jet |
240 |
230 |
270 |
260 |
330 |
270 |
|
Needle jet |
105 |
106 |
106 |
106 |
106 |
106 |
|
Needle position |
3 |
2 |
3 |
2 |
4 |
3 |
|
Throttle valve |
3½ |
3½ |
3½ |
3½ |
3½ |
3 |
|
Pilot jet |
25 |
25 |
30 |
30 |
30 |
622/107 |
Earlier Venom models were fitted with the Concentric type carburetter Type R930/15, which had the following settings :
- Main Jet 270
- Needle Jet 107
- Pilot Jet 30
- Throttle Valve 4
- Needle Set in bottom groove position.
Ignition Timing.
Fully advanced before top dead centre
|
MSS. |
Viper. |
Venom. |
500 Scrambler. |
350 Scrambler. |
|
36° |
38° |
38° |
38º |
38° |
Magneto.
|
Lucas type K1F. Fixed ignition, anti-clockwise rotation. Fitted with Lucas type JY16A Automatic timing unit. |
|
B.T.H. Type BKH1 (Hand controller on Clubman and Scrambler models). |
Coil Ignition
Lucas type
Lighting Equipment.
|
Dynamo. |
Miller. Type DVR 6-volt. |
Belt driven anti-clockwise rotation with Automatic Voltage regulator unit. |
|
Head Lamp. |
Miller Type 79CV, incorporating switch and ammeter. (1955 to Mid 1956). |
|
|
Miller Type 180CV on Viper, Venom and MSS. Lucas type SS700P. |
||
|
Lighting Bulbs. |
Headlamp main bulb. Headlamp parking bulb. Rear lamp. Rear and stop lamp bulb. Speedometer bulb. |
6-volt, 30 X 24W. Bifocal prefocussed. 6-volt, 3W. M.E.S. Cap. 6-volt, 6W. S.C.C. Cap on MSS. 6-volt, 18 x 6W. (Offset pin.), Viper and Venom. 6-volt, .18W. M.B.C. Cap. |
|
Battery. |
6-volt 13 ampere hour. |
Varley, Lucas, or Exide. |
Gearbox
Four speed, constant mesh, foot controlled. Oil lubricated
Gear Ratios
|
Gearboxes, Prefix No. 14 : (MSS.) |
|
|
With solo sprocket (18T) : |
First, 12.4 ; Second, 8.57 ; Third, 6.52 ; Fourth, 4.9 to one. |
|
With s /car sprocket (16T) : |
First, 13.91 ; |
|
Gearboxes Prefix No. 12. (Viper and Venom.) |
|
|
Venom. With solo sprocket (1ST) : |
First, 11.24 ; |
|
Venom. With s /car sprocket (16T) : |
First, 12.62 ; |
|
Viper. With solo sprocket (21T) : |
First, 12.62 ; |
|
Gearboxes Prefix 12 : Suffix R. (Clubman models). |
|
|
Venom. With solo sprocket (18T) : |
First, 9.25 ; |
|
Viper. With solo sprocket (21T) |
First, 10.45 ; Second, 7.94 ; Third, 6.03 ; Top, 5.5. |
Chains and Sprockets.
Primary Chain : .5-in. pitch; .305-in. wide ; .335-in. roller dia.; MSS and Venom 68 pitches; Viper 67 pitches.
Rear Chain : MSS and Venom : .625-in. pitch; .380-in. wide ;
.4-in. roller dia. ; .101 pitches.
.100 Pitches when 16T driving sprocket is fitted.
Viper. .5-in. pitch; .305-in. wide ; 124 pitches.
|
Sprockets. |
MSS and Venom : |
|
Viper: |
Wheels and Tyres.
| Viper Special | 3.25 x 19 | 19-1b. p.s.i. front 24-1b. p.s.i. rear |
| Viper Sports | ||
| Viper Clubman | ||
| Venom Special | ||
| Venom Sports | ||
| Venom Clubman | ||
| MSS | ||
| Endurance |
| Viper Veeline | 3.25 x 19 | 19-ib p.s.i. front 25-lb p.s.i. rear |
| Viper Veeline Clubman | ||
| Venom Veeline | ||
| Venom Veeline Clubman |
| 350 c.c. Scrambler | 3.00 x 21 4.00 x 19 |
21-lb p.s.i. front 16-lb p.s.i. rear |
| 500 c.c. Scrambler | ||
| Thruxton | 3.00 x 19 3.25 x 19 |
22-lb p.s.i. front 24-lb p.s.i. rear |
See page 91 for further information.
Fuel and Oil Capacities.
|
Fuel Tank : |
4¼ imperial gallons. 19.3 litres. 5.1 U.S. gallons. |
|
Oil Tank : |
.5 imperial gallons. 2.27 litres. .6 U.S. gallons. |
|
Gearbox : |
1 imperial pint. .56 litres. 1.2 U.S. Pint. |
|
Front Fork : |
(per strut) .125 imperial pint. 71 cubic cm. .15 U.S. Pint. |
|
Chain Case : |
1/8-pint. 71c.c. .15 U.S. pint. |
Principle Dimensions.
|
Wheel base : (in normal loaded position) 53.75-ins. 136.5 cms |
|
Ground clearance : ( „ „ ) 5.5-ins. 14 cms. |
|
Seat height : ( ,, ,, „ ) 30.5-ins. 77.5 cms. |
|
Overall Width. 27.5-ins. 70 ems. |
|
Overall Length. 7-feet. 213 ems. |
|
Unladen Weight. M.S.S. & Venom 385-lbs. 174 kilograms. |
|
Viper. 380-lbs. 172 kilogram. |