[singleminded]

I agree Ian..
On my Vincent the pressure at the big end feed is around 3psi.
When you consider the little amount of oil used by a total loss system the later recirculating oil systems seem overkill.
My reason for posting about the spring is to try to find a source of commercially available springs that will work,even if they need small adjustments..John

[iansoady]

When I made one for my Model 10, I just wanted a spring that was strong enough to return the plunger when the engine wasn't running but allowed it to protrude when it was. I have a box full of odd springs that I've collected over the years.

TBH, with roller big and main bearings, these engines don't need huge pressure - as long as there is some flow it should be OK (he said crossing his fingers).

[singleminded]

I've just had to make a new telltale for my brother in laws 9A.
I had made one for him before but it and the spring had gone astray, so a new had to be made.
Making the telltale is not a problem but finding a spring is.
I went through my spares,not enough for my liking, and found nothing so I looked in my carburetter parts and looked at a pre-monoblock throttle spring. Obviously too long but cut down to 1 5/8ths inch (1.625" 41.275mm)
it may do the job. I tried it with an old broken timing cover that I have and the telltale pops out and returns,once i have the bike running it will most likely need trimming a little to get what I like from it..John