Hi, I bougt a spare cilinder some time ago. This one has double valve springs; in and outer springs.
Is this the "speedway" version ?
Any ideas ?

Hi Michael..Particularly when the original (single) springs get old it is possible to experience 'valve bounce' at the upper end of the rev range.
The addition of inner springs solves the problem.
However, they should be selected with some care to avoid excessive pressures at the valve seats and the cam/follower interface.
I read in an article that Norton Commando inners were ideal but in fact the spring pressures with these fitted were much too high.
I have used C15 inners and I believe Ariel WNG inners work OK as well. However, with NOS valve springs fitted I haven't really found inner springs to be necessary so currently don't have them fitted...Ian

email (option): ian@wright52.plus.com