Oil pump and circuit

Hi 
Does anybody make or have information on the oil non return valves on the ABC ?
Mine has a spring on the outlet ball valve but not on the inlet. Is this correct ?
Thank you
All the best Andrew Cox

G'day Andrew,
                    First off, congrats on your 300+ kilometre  rides! There doesn't seem to be much wrong with your engine lube system!
(An aside: has Oz renounced the pint as well as the mile? Is your Sopwith held together with 6.35mm. BSF bolts etc?) 
Secondly, no, your inlet NRV is not correct, it should include a spring. It (clearly!) still functions as an NRV, but will allow oil to seep/gravitate/syphon into the engine when it's not running. Do you shut the regulator valve when the machine is not in use?
If this is a serious matter to you, you could switch the NRVs with each other, or just transfer the spring from Exit to Inlet. (The action of the exit/'breather' valve is trivial, as I've remarked before!).
I'm envious of your Spring weather! Please send us some!