The above photos show the BVR (Brian Valentine Racing) SOHC 5 Valve Weslake engine.
The father of Brian is Ron Valentine the original designer of the very first Weslake engines.
After Otto Lantenhammer came with his prototype OHV 5 valver, Brian decided that a SOHC system for the 5 valve should be much better. The engine was tested in a grasstrack bike and was very promising, but the project was stopped by the FIM because very shortly after the engine was tested, they came in with new regulations for speedway and longtrack racing.
The new rule stated that only engines with 4 Valves could be used in speedway and longtrack racing.
Many thanks to Ben Ludolphy from the Netherlands for supplying one of the pictures and the information on this one.