Atlas Wet Sump Shut off Valve

I'm very aware of all of the conversation concerning wet sumping but want to throw this question out there. My Atlas uses 1/2" id supply and return hose because of the barbed ends on the oil tank fittings and manifold pipe. The ID of the stock oil supply and return manifold pipe is 5/16. There's only 2-1/2" between the end of the manifold pipes and tank fittings so the opportunity for a valve is limited. I did find a valve that would fit but the bore is only 1/4". Here's the question would necking down the supply line to 1/4" ID at the valve be detrimental to the oil requirements of the engine. I suspect I know the answer. I might just get over the whole thing and drain the sump when required

The necked area will increase the frictional losses but due to its short length not enough to be concerned about. But better to go for a sump plug with small drain plug and drain, filter oil and return to oil tank. The speed of the drain tells you how worn your pump is.

One example of the sump with drain plug so you don't wear out your sump threads or get leaks from disturbing the joint too frequently.


AN do one too

Your engine will still get plenty of oil up top with the necked down fitting. However, you might as well get the sump plug kommando linked to and drain the sump after the bike sits more than a couple of weeks. It would be a lot less work to fit, and your bike would look cleaner without a shut off valve. I do use a shut off valve with ignition cut off when shut, but only because my 2 into 1 exhaust goes into the collector right under my sump plug.

kommando said:

But better to go for a sump plug with small drain plug and drain, filter oil and return to oil tank.

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Do you have a recommendation on what to use to filter the oil? I drain mine this way. My N15 has little room for a switch or filter so I drain it when needed - which is less now that I refreshed the pump, but it still will sump after a long period.

The filter you use depends on the time you have, a simple paper cone coffee filter works but is too slow, a course metal will speed things up but not filter well. You could keep coffee filtered oil for topping up and then filter the drained oil at your leisure to be the topping up oil for the next ride.

kommando said:

The necked area will increase the frictional losses but due to its short length not enough to be concerned about. But better to go for a sump plug with small drain plug and drain, filter oil and return to oil tank. The speed of the drain tells you how worn your pump is.

One example of the sump with drain plug so you don't wear out your sump threads or get leaks from disturbing the joint too frequently.

MAGNETIC SUMP PLUG COMPLETE (LARGE)

SUMP PLUG BODY AND DRAIN PLUG STAINLESS STEEL. REST OF THE PARTS AS ORIGINALALSO SEE PART NUMBERS: 067676S, 067676 AND 067676MS

www.rgmnorton.co.uk

AN do one too

Andover Norton - MAGNETIC CRANKCASE (SUMP) FILTER KIT - 06.7281

MAGNETIC CRANKCASE (SUMP) FILTER KIT

andover-norton.co.uk

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Thanks Kommando. Increase in frictional losses means what? A decrease in flow. I do have that sump plug installed

Schwany said:

Your engine will still get plenty of oil up top with the necked down fitting. However, you might as well get the sump plug kommando linked to and drain the sump after the bike sits more than a couple of weeks. It would be a lot less work to fit, and your bike would look cleaner without a shut off valve. I do use a shut off valve with ignition cut off when shut, but only because my 2 into 1 exhaust goes into the collector right under my sump plug.

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Thanks. What’s your valve look like and what is its bore?

jms said:

A decrease in flow.

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Yes, but check the holes in the crankcase where the manifold sits, they are small too. So nothing to worry about as its a tiny amount.

jms said:

Thanks. What’s your valve look like and what is its bore?

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It is a Feked anti-sump valve with ignition cutoff. Bore is around 11/32". Not real pretty. Shown below with the valve handle in the Off position and my ignition key hanging off of it.

The decreased flow to the pump is insignificant in real world use on the street. My pump feed line runs under the gearbox and up to the pump. All of the feed is lower than the bottom of the oil tank. The oil pump does not starve for oil, nor do the spindles, rockers, valve tips, push rods, or cam lobes.



I'm not recommending this solution on this website although it is one if a Norton sits for long periods of time not being run.

I have one of these on My N15, can be used with magneto and points.

Here is a picture of my 1962 Norton 650SS, (so probably very similar to your Atlas) with a "Magneto Guys" tap fitted. Electronic cutout to the mag cover, easy to install, works great! Although it required shortening the oil feed pipe on the oil pipes junction block in order to get it to fit: