40M Engine Specification

Bore 76mm
Stroke 76.7mm
Capacity 348cc
Crankshaft Machined from one piece of EN40B steel and nitrided
Connecting rod Forged steel with plain big end and bushed small end
Piston Forged alloy, 2 rings, cross braced pin bosses, low friction coating
Crankcases & covers Machined in-house from precision magnesium castings
Main bearings Works type flanged double ball race on timing side. 2 x needle rollers on drive size
Oil pump Bronze body, as original works bikes but with F1 style modern porting
Cam drive Bevel driven vertical shaft with splined tube (as 1959 on)
Magneto drive Via toothed belt
Barrel Machined from solid alloy
Bore Nicasil plated
Head Machined in-house from precision L169 alloy casting. Ported by hand
Valves Plasma nitrided stainless steel, lighter than original
Valve actuation As original, direct acting DOHC
Valve springs Double helical springs, fully enclosed in magnesium castings
Pushers Lighter than original with low friction coating
Carburettor * Amal GP
Ignition * PAL magneto
  * Items marked thus are not included if engine is purchased separately
  Please note that Works Racing Motor Cycles Ltd. reserve the right to alter specifications at any time