What is this spigot of ES2?

This is my first post from Japan, thank you all for your help.

What is this spigot of ES2?

Can anyone tell me what this spigot at the junction of the primary case and crankcase is for?

A hose is attached to this spigot and at some point it suddenly started leaking oil. It was not leaking before.

Haru

Is that the bottom of your primary drive chain case? Cj

Hal said:

This is my first post from Japan, thank you all for your help.

What is this spigot of ES2?

Can anyone tell me what this spigot at the junction of the primary case and crankcase is for?

A hose is attached to this spigot and at some point it suddenly started leaking oil. It was not leaking before.

Haru

Click to expand...

That looks strange to me - not very much like an ES2 (I have one -1962)
Maybe shine a torch on the area when taking the photo.
Your photo is very dark.
Cheers

When checking on Andover Norton website, pre featherbed models, it might be in the place for a drain plug.
In my spare parts list for 1959 models (with alternator) it can't be seen.
My guess is that a spigot instead of a plug makes it easier to drain a badly wetsumping or rarely used engine.
Will go and check on my ES2 when daylight.

Thank you all for your responses.

This is between the crankcase and the primary chaincase.

I will open the primary chain case next time to check.

Hal said:

Thank you all for your responses.

This is between the crankcase and the primary chaincase.

I will open the primary chain case next time to check.

Click to expand...

Ignore my previous post.
Better picture, explains more. My guess: Looks like you have a 1959 or later ES2. Because an alternator model. Mine is a -55 so a magdyno.
The spigot is fitted on the stator housing. No mention in parts book as far as I know. Luckily never had to take apart a ES2 (yet).
I think the reason might be to drain crankshaft seal leakage from overfilling the primary. But I don't know anything about crank seals.
If you fit your spigot to a plastic tube ending in a small bottle placed between rear engine plates you can check how much it leaks. Same as the mandatory catch tank used on roadracing bikes.
I should not worry if just a few drops.
As usual on most British bikes, if left unused for a week or more, draining of crankcase needed before start. Seen a 650SS completely fill primary after shooting crank seal.

Mike, thank you so much for your advice.

I had also guessed that the spigot was to drain a little bit of oil that had built up inside the housing for some reason.

If it was just a few drops of oil it would be fine, but at some point it started to heap up in large quantities, so there could be a problem with the crank seal being out or something.

In any case, the primary case may need to be dismantled and checked once.