Wet sump idea....

[limeyrob]

Has anyone tried putting a slight vacuum on the oil tank when parked for a few days?  I've got a spare primer bulb that is for priming an outboard and I'm thinking I could put this on the breather tube from the top of the oil tank and give it a few pumps when I park up.
My thinking is that I only need a slight vacuum to stop the oil draining as its only about 2 ft head and its fail safe (ish).
Tell me all he reasons why this is stupid idea now before I try it and find out the hard way.

[Greybeard]

If the one-way valve behind the pump is in good condition you should not get much oil in the sump.

[limeyrob]

If only it was that simple .  I rebuilt my engine, new ball, spring, re-seated, checked.  What could go wrong?
A lot it seems since the sump gets about 1/4 pint a week.
Pump was old but rebuilt by me with lapped faces.
So my options are limited and since the engine is running well I want to leave it alone. I could stump up for a SRM pump but its not really justified for this one issue.
I looking for non-invasive solutions that are not a tap on the oil feed.
At the moment I drain the oil off before a ride and put it back in the tank

[CheeserBeezer]

Good lateral thinking but... I'd be surprised if you were able to achieve a sustainable vacuum as the suction will pull the oil out of the rocker feed on the return side. On the feed side it will pull oil through the pump from the timing side bush, which is quite undesirable actually!

[limeyrob]

Yes that's the conclusion I'm coming to; all I may achieve is a dry  valve gear.
Since its an easy test I'll give it a try in the next week or two and report back.

[Black Sheep]

My Norton wet sumps. If I'm going to leave it for more than a fortnight, I just drain the tank into a 5 litre container until next time I use it.

[Ted_Flash]

Hot oil will syphon.  On return from a run I syphon it out into an oil can and then put it back when needed for the next outing.  A piece of wire wrapped round kickstart and oil filler neck prevents forgetfulness.  Just make sure the syphon pipe is secured as it has to be left to do its thing for half an hour.  Saves messing with draining the sump.

[Greybeard]

But if there is only a small amount of oil in the sump, starting the engine and let it tick over will pump it back into the tank.

[Rex]

Get yourself a Velocette single; those bikes have anti drain-down valves which actually work, and IIRC someone has used this component on non-Velo engines too.
Easy fit (possibly) as it screws into the base of the oil tank and connects to the feed oil line.

[Worty]

Hot oil will syphon.  On return from a run I syphon it out into an oil can and then put it back when needed for the next outing.  A piece of wire wrapped round kickstart and oil filler neck prevents forgetfulness.  Just make sure the syphon pipe is secured as it has to be left to do its thing for half an hour.  Saves messing with draining the sump.

The vacuum idea won't work, I've tried it with a brake bleeder pump and it just won't hold any type of pressure.  As you all know (and I can hear you sweating right now), I have a tap on the feed and it prevents all the fuss of draining the sump and putting the oil back in the tank (takes about 10 seconds to switch it on/off).  I still have a very good memory and a set routine for preparing the bike for a ride, so never forget to switch the oil on.  If I did ever come close to forgetting, I'd do the same as Ted (or write OIL on a note and put it on the tank)

[BSA500]

I use the tap thats connected to the mag. Oil switch closed and the mag is earthed so wont start. Oil tap open mag not earthed engine starts 

[Worty]

I use the tap thats connected to the mag. Oil switch closed and the mag is earthed so wont start. Oil tap open mag not earthed engine starts 

They're good kits.  The main difference (apart from peace of mind) is that the tap cost me around £12, but the maggy set-up is considerably more last time I looked.

[Swarfcut]

 A well sealing filler cap and a taper bung in the tank breather should prevent air entering the tank and allowing drain down. Worth a try, simple and quick.

 Vacuum is fine in theory, but too much and it will draw oil, then air from both feed and supply side. Sealing the tank offers a possible solution but again, like a cliff railway oil can flow down to the sump under gravity, replaced by oil drawn up from the sump, then air.  But it may give the anti sump valve that little bit of help it needs.

 Swarfy.

[Worty]

True Swarfy, I couldn't get any vacuum reading at all after a number of tries.  As with your explanation, the return is above the level of the oil in the tank which would mean oil, then air will be sucked continuously into the tank preventing any vacuum build up.  As the engines are rarely oil tight, I reckoned they're definitely not going to be air tight.

[BagONails]

Has anyone had experience with those 'anti wetsumping valves' that go into the oil delivery line between tank and engine?

They were marketed by a person called Polly Palmer under the Bri-tie brand name. Unfortunately Mr Palmer has I believe passed and I can't find any further references for the valves so not sure who actually makes them. I think they are a simple mechanical device that opens as soon as the oil pump creates a drop in pressure on the engine side of the valve as long as the engine is running the valve stays open, you hope, and when you shut down and the pressures either side of the valve equalise it closes and prevents more oil passing through under gravity until that is you kick the engine over again.

Simple and effective but with the potential to spoil your weekend if it sticks closed. Having said that there seems to be a large following who swear by them and have never seen or heard of a failure...I'm not sure I could live with the nagging doubt though...