Viper. Venom and MSS.
Bore 72 mm. 2.8347-in. 86 mm. 3.385-in.
Stroke 86 mm. 3.385-in. 86 mm. 3.385-in.
Capacity(swept vol.) 349 c.c. 21.29 c. in. 499 c.c. 30.45 c. in.
Rated Horse-power (A.C.U. Rating) 3.5 5
Running tappet clearances: .005-in. .005 -in.


 Engine serial number and prefix stamped on left hand side of crankcase just below cylinder base flange. See page 34.


 Overall ratios with standard driving sprocket on gearbox : *

  Viper Venom MSS
1st 12.6 to 1 11.2 to 1 12.4 to 1
2nd 8.73 to 1 7.74 to 1 8.57 to 1
3rd 6.64 to 1 5.88 to 1 6.52 to 1
Top 5.5 to 1 4.87 to 1 4.87 to 1

 Gearbox serial prefix and number stamped on top of housing on right hand side.


Fuel 3 Imperial Gallons; 13.6 litres; or 3.6 U.S. Gallons
Oil ½ Imperial Gallon; 2.27 litres; or 0.6 U.S. Gallons 


  Viper Venom and MSS
Engine Sprocket 21T 23T
Clutch Sprocket 44T 44T
Gearbox Sprocket 21T 18T*
Rear Wheel Sprocket 55T 46T
Primary Chain .5 x .305-in. 67 P 
Roller dia. .335-in.
.5 x .305-in. 68 P *
Roller dia. .335-in.
Rear Chain  .5 x .305-in. 124 P
Roller dia. .335-in.
.625 x 380-in. 101 P
Roller dia. .335-in.


  Viper Venom MSS
Front Rim WM2 x 19 WM2 x 19 WM2 x 19
Rear Rim WM2 x 19 WM2 x 19 WM2 x 19
Front Tyre 3.25 x 19-in Rib 3.25 x 19-in Rib 3.25 x 19-in Stud
Rear Tyre 3.25 x 19-in Stud 3.25 x 19-in Stud 3.25 x 19-in Stud


Serial number and prefix stamped on right-hand side of front seat lug

These are running clearance set cold. Different clearances must be employed for checking valve timing. See page 40 before checking or adjusting.

Always quote the engine serial number and prefix on all orders for spare parts and in any correspondence with the factory.

 *A smaller sprocket and shorter chain are used if a sidecar is fitted.