Oil feed cut out tap

[Marcush757]

I’d like to fit an oil tap with an electrical cut out switch to alleviate the regular draining of the sump every time I take the bike out.

Just wondering if anyone has fitted a device similar to the one that The Magneto Guys sell?


https://www.themagnetoguys.co.uk/oil-ta ... out-switch

As far as I can see, there are a number of ways to fit the tap.

1. Straight off the tank outlet. However I don’t believe there is enough room for this option as it is too close to the inlet pipe.

2. In-line somewhere along the rubber oil pipe. Possible

3. Fit directly onto the engine case. Possible.

I’d also like to renew the old rubber oil pipes at the same time, however I’m unsure how to replace the banjo joints on the engine case as the rubber pipes have a crimped brass ferrule. Not a problem at the tank end as the pipes here have jubilee clips.

Any advice welcome.

Many thanks.

[limeyrob]

If you do a web search on the matter of anti-wet sumping valves you will find extensive and sometimes heated discussion on this issue on most bike forums including this one. I will not summarize that here, suffice to say there are strong opinions both for and against with stories of success or seized engines. I'll put my cards on the table and say I'm in the "against" camp but I have just had to run both my bikes this afternoon as I've been away for a week. They (a G3 and a BSA A10) can both stand for about 2 weeks before there is a problem so a weekly start up or ride is enough.
What I will offer as advice is:
1 - be careful with the engine connections into the case, it is easy to damage the threads and turn a small job into a very large one. You can remove those crimped ends and fit clips or new crimped ends.
2 - these bikes did not wet sump significantly when new and many still don't now. The best prevention is a good condition oil pump that seals when standing and it is worth spending effort on that rather than the work around of a tap.
3 - bikes that are in regular use seldom wet sump to the point that its a problem. Try leaving the bike standing for (say) a week then time how long the oil return takes before there are bubbles. With a few experiments you will get a feel for the rate the sump fills. If it smokes badly of course that's too long.

[Marcush757]

Thanks very much for the input. Yes I've done a fair amount of reading up on the web regarding this issue and appreciate the pros and cons of fitting a tap.

After a week of standing, the sump has a pint of oil drained out every time. As I use the bike infrequently, it becomes a real chore each time I wish to go out. I presume this indicates that the oil pump needs attention at some point and therefore I thought that the short term fix would be a tap. I'd prefer to have the pump rebuilt but am unsure how difficult or costly this would be. I doubt this would be something I could do.

[limeyrob]

That's interesting. My BSA A10 would dump a similar amount and on that engine I had fully rebuilt the anti-sumping valve in the engine. The oil was draining out through the pump which casts doubt on the pumps ability to pump too. A new precision pump (about £300) has cured this so it drains about half a cup in 3 weeks, hence my comment that the condition of the pump is crucial.
The pumps (only the feed really matters) are quite easy to get to and its worth seeing what condition its in. It could just be a matter of lapping the faces if its the gear pump.

[Steven S]

A factory service bulletin from 1956 states that a pint is normal after a "short period", a typically vague description. So that's how they were when new, though of course most bikes were used daily so it was academic for most owners.

[Andy G]

It might make kick starts a bit harder, but if it's a pint per week, I'd experiment by not draining, accept initial smokiness, and let the pump do it's thing to recover the oil to tank?

Of course, if it's a long period, you may find excess oil in the chaincase, but that's easier to drain.

[desperate]

I've not noticed any bad effects from wet sumping, the oil level does seem to drop maybe an inch and a half in a few days but it starts fine with no noticeable smoke and fills the tank back up within 20 seconds or so. I use it pretty regularly but there have been a few occasions where it has been parked up for a few weeks, so far the chaincase oil level seems to stay pretty much static. I would suggest if it starts ok without loosing too much into the chaincase leave it be. Too risky IMHO.

Desp

[g80csp11]

The risk of wet sumping is , in extreme cases
1) engine more difficult to kick over
2) Over oiling on bores when started causes oil to get past rings , and into exhaust system/soot plug up
3) Oil gets into primary chain case if oil level in sump gets high enough , especially if bike is left on side stand
4) temptation to top up oil in tank , resulting in over full tank once started

all of these are best avoided if possible

Personally , if you want to fit a oil tap that's OK , but should have a electronic switch as accidents happen , and loss of oil to the engine is expensive . we hear so many stories !

You can get switches with cut out , one for magneto and the other for coil ( anti-sump-tap-switch-mag-B2 ) for circ £58.65 + VAT and delivery

As Steve says , oil pumps will always wet sump slightly due to head of oil , viscosity , wear

[limeyrob]

We all know wet sumping can be a problem on old bikes. What I was looking at was what is the hierarchy of mitigation? My best shot is:
1 start or ride the bike weekly if at all possible.
2 fit the best condition oil pump you can get your hands on.
3 fit an easy to remove drain plug or a bleed nipple in the drain plug
4 fit a tap in the oil feed
1,2 are no risk to the engine, 3 is modest and 4 is considerable risk but it is also guaranteed to solve the problem. My point is fitting a tap should be the last option not the first. If you follow Paul Henshsaw on YT (he has a classic bike repair shop) you will see he has had in customers bikes with sized engines due to oil taps. An ign interlocked tap reduces risk but adds complexity and another failure mode plus complacency.