I have been following this topic with great interest as probably every other A10/A7 owner has.
I had a one way valve fitted by the PO which solved the wet sumping but as the bike had not been used on the road since an engine rebuild, following advise from this forum I removed the ball from the one way valve before I used the bike on the road.
Since then I have suffered from wet sumping which, if left, will fill up the sump and eventually the primary chain case in a few weeks. As a temporary solution I remove the sump plug and leave it out after a run and let the oil drain into a filler can and keep putting it back into the tank through a gauze filter every week or so. This avoids having to drain the primary as well as well as the sump.
The Carritek valve looks similar to the Dove valve which I purchased a while ago but have never fitted. The problem with the Dove is that the oil pipe bore is suited to an AMC (which is what it was designed for) rather than a BSA and is too big for the BSA pipe. I know it is possible to use adaptors etc but there is not a lot of room below the oil tank to fit a valve and it would look like a dog' s dinner with loads of clips and adaptors running across the top of the gearbox. Fitting below the gearbox would involve burnt fingers on the exhaust when using the valve. I know the exhaust should be cool when turning the oil on but I would like to operate the switch after a run to check that the mag is killed.
I see no problem fitting a suitably sized valve with a kill switch incorporated as it is inherently fail safe. Even if the switch falls off the tap, provided the wires are still connected it will still kill the mag provided a "break" switch is used - ie the normal position of the switch gives a cicuit across the contacts meaning that the mag is killed. Another procedure after a run would be to use the oil switch to shut the engine off instead of the kill button which would prove the kill element on the oil tap is working. Personally I always take the oil cap off when starting to check the level and to ensure oil return.
The only risk element in the setup is if the earth brushes in the mag fail or if the wires fall off the mag end cap or the earth point or if there is a break in any of the wiring, or if the switch itself goes open circuit and allows the bike to be started with the tap closed. There has been a recent thread regarding the wrong type of carbon in mag earth brushes so there is a small risk. I appreciate that the above risks, although very small, may be too great for some and the only truly safe system has no risks at all.
Both valves mentioned above look to be standard plumbing ball valves with the nylon handles ground away to act as a cam to open the switch. This seems a bit crude and I think would be more sound if a metal tap handle and operating cam were fabricated. If the setup were to be used for coil ignition then a "normally open" switch would need to be used rather than a "normally closed" for a mag. Alternatively a changeover switch could be used which would cover either setup. The switches should be weatherproof (and preferably not made by Lucas
)
The A65 non return ball valve system seems to be a bit suspect as the oil flow needs to pass around the ball so this does not appear to be a viable mod. According to other posts, replacing and reseating the existing ball and spring seems pointless as there is opinion that the return spring is too weak.
I do not have an answer for the wet sumping problem - I wish I did then perhaps I could make some money
I will continue to monitor this subject in the hope that other members a lot smarter than me can come up with a solution.
Jim