Oil valve solution to oil falling to crankcase

[Fast Eddie]

Last spring, after I’d been working in my Triumph a lot, I dragged the Norton out.

Triumph‘s don’t wet sump.

The Norton had had fresh oil etc prior to lay up.

I fiddled with a lot on the Norton and then plain forgot to empty the sump.

So I pressed the button on the cNw starter and it fired right up… 920cc at 11:1 CR and a sump FULL of oil…!

Learning points from this ‘experiment‘ were:

1. The cNw starter is amazing. I’d argue it puts out more power than some Commando engines !

2. The Comnoz designed breather from NYC Norton does an amazing job of emptying sump oil to the tank. Remember, I didn’t kick it over at all, just press and BROOM. Yet that sump full of oil just returned to the tank, and the oil seal remained perfectly fine.

I’m not suggesting that the above is what one SHOULD do, but it’s reassuring to know that this is all that’s likely to happen in the event of forgetting to drain the sump.

@ the OP, do yourself a big favour and get one of these:

Reed Breather Kit

The Norton twin cylinder engine creates a serious amount of pressure in the crankcase as the motor spins. Over the years the factory attempted several methods to reduce this pressure – from a timed breather off the end of the cam on earlier motors, to a crude straight pipe from the timing chest on

nycnorton.com

 

[jseng1]

A cheap easy way to keep the main seal from blowing its lip out is to add the Oring as in photo. The lip has no where else to go so it stays in place - making it a high presure oil seal.

Install a 1-1/8" ID 3/32 wall viton oring between the primary sprocket and the main seal. Its a #122 oring - you can get them for cheap at suppliers like Mcmaster Carr. This fix costs a dollar or less and can save you an hours+ worth of labor. The photo shows the fit on a 750 and 850 Mk2. Not sure how it fits on a Mk3 (should be the same but not verified). I measured about .010 or so clearance between the oring and the primary sprocket.

 

[KiwiShane]

If you have the Comstock breather its this easy

 

[javifoto70]

After reading you all I will go for the Oil tap with cutout switch solution. I think is the most simple, cost effective and more suitable solution for the kind of use I will give to my Commando. I like the Reedn breather kit too but it is too expensive (also considering the shipping cost from US) for me.
Opening another tap before starting the engine as I do with the petrol taps on any classic bike is not an issue for me.

 

[Fast Eddie]

The fact that the sump type breather helps with the oil return is only a side benefit!

Its real function is a breather. It allows gasses out but not back in. This prevents build up of internal pressure that is often the cause of many frustrating oil leaks.

 

[javifoto70]

I see your point. So for this useful purpose may I alternatively install this model I can get in UK?

PCV BREATHER CRANKCASE VACUUM NON RETURN VALVE

064862 RGM NORTON PCV NON RETURN VALVE F68

www.rgmnorton.co.uk

If it works in a similar way as the NYC Reed breather I can maybe install it and also install the oil tap with cutout switch.

 

[Fast Eddie]

I see your point. So for this useful purpose may I alternatively install this model I can get in UK?

PCV BREATHER CRANKCASE VACUUM NON RETURN VALVE

064862 RGM NORTON PCV NON RETURN VALVE F68

www.rgmnorton.co.uk

If it works in a similar way as the NYC Reed breather I can maybe install it and also install the oil tap with cutout switch.

No idea what is inside that, or how it works, or how well.

I have successfully used the ones sold by hNw before though, as have many others, about 3/4 down this page…

exclusive Commando parts | Holland Norton Works

www.hollandnortonworks.eu

 

[Schwany]

After reading you all I will go for the Oil tap with cutout switch solution. I think is the most simple, cost effective and more suitable solution for the kind of use I will give to my Commando. I like the Reedn breather kit too but it is too expensive (also considering the shipping cost from US) for me.
Opening another tap before starting the engine as I do with the petrol taps on any classic bike is not an issue for me.

If you plan to enhance the Norton breather solution, whatever it is, the reed type breathers work much better than an inline automotive PCV valve.

An inline PCV valve does not work like the NYC breather. Not even close. It will let air escape though.

 

[texasSlick]

That device shown in the link above (post #26), is NOT an oil tap shut off device. It is a non return breather similar to the NYC Reed breather.
Depending on where and how you install it will determine how effectively it purges the crankcase of excess oil. The NYC breather replaces the large sump plug at the bottom of the crank cases where excess oil collects and oil will be expelled when the pistons descend. The RGM device is worthwhile as a breather, but it will not, of itself, cure the wet sumping problem, nor allow excess oil to return to the oil tank, unless you can tap the crankcase low down. IMO, the NYC sump plug breather is worth the cost. Have one on my Atlas.

Slick

 

[worntorn]

I'm not sure that any breather should be added to the MK3 arrangement if the oil separator is to be retained.

Some owners do away with the separator then add a reed valve.
My 920 is a MK3 engine with the separator and lines removed, reed breather added.
It seems to work OK.

My 850 MK3 retains the stock breather system and oil separator.
It also works fine, it's a very dry bike, like a modern.

Glen

 

[Mart UK]

My ignorance, what is the 'oil separator'?

 

[L.A.B.]

My ignorance, what is the 'oil separator'?

Andover Norton Parts Drawings - Genuine Andover Norton Factory Parts - Commando Parts

Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.

andover-norton.co.uk

Item 34 (Assembly)

Andover Norton - BREATHER SEPARATOR UNIT (ASSEMBLED) - 06.5573

BREATHER SEPARATOR UNIT (ASSEMBLED)

andover-norton.co.uk

 

[Anglophile]

A lot of people poo-poo a valve but I have used: Anti wet sump valve #H08 from Holland Norton Works for ten years and it's been great.

(of course I do use an oil light from Madass)

 

[Deets55]

I use the factory separator and Comstock sump breather. I just deleted the small hose to the intake manifolds coming from the separator and installed a drain hose from the bottom of the separator. Every once in a while I will get some condensation dripping from the drain. Works for me.

 

[Fast Eddie]

Does anyone have a diagram of how this oil separator works inside ?

 

[Schwany]

I use an air compressor oil separator in line off the oil tank froth tower hose that used to dribble out to a chain oiler I think (not a Commando). It is located close to the upper shock mount and has a conical filter at the end of a hose 12" or so past the shock mount.

I will not discuss my anti-sump solution without a lawyer present. lol

 

[Deets55]

Does anyone have a diagram of how this oil separator works inside ?

Nigel,

It has no moving parts. The hose from the top goes to the oil tank, a small metal tube on the side of the separator goes into the plastic air box. On the bottom a tiny metal pipe with a 'U' shaped bend attaches to a plastic hose and goes to the intake manifolds with a "T" fitting. The separator itself is nothing more than a vinyl tube that the hoses and tubes attach to. I believe the way it works is, the small tube that goes to the manifolds pulls a vacuum into the separator. This in turn vents the fumes from the oil tank to the separator and directs them into the air box. More of an emissions thing than anything else. That's just my take on it.

Pete

 

[worntorn]

Does anyone have a diagram of how this oil separator works inside ?

This diagram shows the breather circuitry, but doesn't really show how the separator works.
It all seems to work on my bike so I've been reluctant to mess with it.
The earlier 850s with plastic airbox might have the same breather/ separator system?


Glen

 

[Schwany]

This diagram shows the breather circuitry, but doesn't really show how the separator works.
It all seems to work on my bike so I've been reluctant to mess with it.
The earlier 850s with plastic airbox might have the same breather/ separator system?


GlenView attachment 103062

Everybody building a Norton engine should have that image on the wall in their shop.

 

[L.A.B.]

I believe the way it works is, the small tube that goes to the manifolds pulls a vacuum into the separator.

Also draws any condensed liquid that collects at the bottom of the separator into the carb inlets manifolds.