G&S Valves Ltd has been serving the automotive and motorcycle industries since 1946, earning the reputation of one of the highest-quality valve manufacturers worldwide. This inlet valve is suitable fitment for the BSA A50 500cc twin-cylinder models from 1966-1969. Also compatible with the 1967-1970 B25/C25 and 1968-1970 Triumph TR25W single-cylinder models.
The V255 replacement inlet valves from G&S are manufactured from high-grade stainless steel to original specifications and have a head diameter of 1.452″, stem diameter of .3105″, with an overall length of 3.677″. Made in the UK.
Inlet valves allow the ingress of the fuel/air charge to the combustion chamber when opened. It’s critical the valve seats and valve faces make a seal when the valves are closed to maximize compression. The valve stems must have the correct clearance within the valve guides to be properly lubricated and dissipate heat.
The cylinder head must be removed from the engine to access the valvetrain. A valve spring compressor is employed to compress the springs far enough to remove the retaining collets from the top collars. Once fitted into the valve guides, the replacement valves will require “lapping-in” to the valve seats. Refer to the factory workshop manual for the complete instructions. Replacing valves is a multi-step procedure and may be best done by a professional machinist.
Note: This listing is for the inlet valve only; guides, seals, and springs are sold separately. Always verify your existing valve size and head modification status before ordering if you have an opened‑up or modified cylinder head.
For Complementary BSA 650 Exhaust Valves (68-0662/V256).
For BSA Valve Keepers CLICK HERE
Read our article: The Legacy of BSA Motorcycles from A10 To A65 Through A70
The product images shown are for illustrative purposes only and may not be an exact representation of the product received. Manufacturers occasionally make minor cosmetic changes to items, such as color, finish, label, or design. These changes do not impact the item’s function or compatibility. Please contact us if you have specific concerns regarding appearance.
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