See if I can get this in before LAB closes the thread.
I have not and would not bother since there are several crankcases involved (e.g., 750 before 72, 750 after 72, 850 before MK3, MK3). Optimal for the breather's actual job is anywhere above the running sump oil level at speed. The side effect of quickly removing excess oil in a web sump condition doesn't matter much because the oil pump will do its job and the breather only gets the excess out quicker - the less of that done the better because it does not go through the oil filter on those bikes with one.
With a full wet sump there is no pressurized oil feeding crank crank bearings, just sitting in oil. Is that of concern? What about no feed to rockers until pump gets fed?If your engine is completely wet sumped then there is plenty of oil in there to lube the con rod bearings - the bearings will dip into the oil every revolution until the oil pump takes over. Oil will also be splashed onto the camshaft the 1st revolution. It only takes a few squirts of sump oil into the oil tank for oil to enter the hose to the oil pump. Norton motors are blown up by shut off valves left closed. Not by wetsumping. I've let mine wet sump over 40 years - the only problem was me overfilling the oil tank once and then blowin out some oil. Adding a 1/16" cross section O ring next to the crank main seal keeps it from blowing out (see photo).
The standpipes can be different lengths. A case with an oil dam in it will need a shorter standpipe. Without the dam the stanpipe can be taller as long as it clears the flywheel.
So due to asethetics, you choose to live dangerously ;-)See if I can get this in before LAB closes the thread.
I bought a Feked ball valve - $50 something US. It is huge. They show the measurements on the site, but I was not paying attention when I bought it. It's in a tool box drawer now. I use a smaller manual ball valve with no electrical cut out. Not recommended for the gen pop. If I blow my engine up, I won't be blaming it on the ball valve. It will be because I am a dumb ass and forgot to open it before starting the bike. I also have a reed valve, but at the rear of the timing cover. It is only for relieving crank case pressure.
The smaller valve that I use shown below has slightly larger 3/8" I.D. hose fittings than the Feked part. Absolutely not recommending this red handle no cut out switch ball valve solution.
Crank bearings, not really a problem as they are well oiled even without pressure in this case - for one thing, the crank is partly to completely full of oil and the force of it spinning will add oil to the shells.
Thanks JS! Do 850s have an 'oil dam"? Which Commandos do not? Also, it'd be good to have your input on the question in post #269
Those with the "1972" cases, including Combats, could have that problem - no others. Those cases do not have the big sump plug. It was not an oiling issue for Combats, it was a main bearing issue. At high enough sustained speed the oiling issue affected those with that case, not just Combats. If not racing, it is highly unlikely that there will ever be a real issue with the 1972 cases. Combats (and the rest) are reliable on the street as long as the correct main bearings are used.
Not about aesthetics. That big valve won't fit easily where I want it to go. Putting off trying to install it until after I get a TTi box in the frame. TTi box won't show up till February or March 2024.
It does not sound serious, there will be residual oil.
IMHO, zero pre kicks. If very wet sump'ed, it probably won't start for a few kicks as you'll have trouble making it spin fast enough. There is the chance of blowing the crank seal, but Nortons were started for a very long time before the sump reed valves came into use. With a sump reed valve, I simply start them.
The JS instructions didn't mention wet sumping, they were more about how to get the most effective power increase from the valve. I haven't noticed extra power, but it seems reasonable if the crankcases are at near vacuum, then the pumping effect of those two cylinders going up and down wouldn't be taking power.