This is the valve retaining collar of the type fitted to Douglas 2 3/4hp models, used to retain the valve springs by means of this collar and a steel pin that fitted through a hole at the end of the valve. The collar is CNC manufactured from EN24T to the original design - which means there is a central rececss to hold the silver steel pin captive, but the collar can revolve around the valve stem.
The collar is CNC manufactured from hard wearing EN24T
Note: I am told this was the original design specification for these collars for the Douglas 2 3/4hp, therefore this item is made as per that design. However, we also offer a modified design of this collar and pin (Item 0729), whereby the collar has an additional slot milled in the recess.
When I originally manufactured these collars, I took the design from an original collar which had a similar slot recess. I cannot be sure if this was just wear to an original type collar, or if someone had modified that collar - but from an engineering perspective I feel the additional slot is a better solution as it should ensure the pin is more captive, and more importantly stops the collar from spinning around the valve - I have a couple of examples of old valves where there is clearly a wear groove on the top of the valve where this has happened. I am not an expert on this engine in use, hence I offer both types (however, I am building my own project bike with the modified design, and will report back once the engine is running)
This listing is for the original type - consisting of one collar and one silver steel pin (4 required per engine)