AJS & Matchless Owners Club

Can anyone tell me what the small pipe (arrowed) is for please? My G15CS has the incorrect oil tank fitted and does not have the small pipe.

As a guess, the rocker feed for a Norton engine (some one who knows will correct me), not a lot of pipe under that to connect to though.

I think the tank in the photo has been modified as none of my bikes with the later rounded shape (singles, G12 or G15) have the small tube take-off. The Norton engine rocker feed on the G15 comes from the oil pump housing on the crankcase not the return oil line.
It probably is for rocker feed but not on any AMC machine.

I too haven't seen a late AMC tank with this fitting.

It could be a rear chain oiler similar to late Ariel singles and twins? They have a similar pipe on the return line. A rubber pipe then runs down to lubricate the chain just above the gearbox sprocket.

I thought that was the return side. I have seen quite a few G15 (Hybrid versions) tanks with this pipe but not actually seen one on a bike.

I've seen many G15 tanks with this pipe James, so I don't think it's modified. There is even one for sale/on show in Russell Motors shop window, unfortunately Les also doesn't know
what it's for....and if Les doesn't know what chance have we got of knowing.
My tank does not have one because it is not a G15 tank, it didn't even have the spigot on the back for the crankcase breather, until I had one brazed on oil used to spew onto the garage floor when I started it.
If you search G15 oil tank on eBay you will see others the same (ignore the ones from India of course).

Very strange then Peter - my brother and I have 8 bikes between us with the later rounded oil tank and none of them have this take off, we have a spare twin tank (with the shield holes) and this too doesn't have it. I've not even seen it on a "slab sided" tank.
My initial thought was that it could be for something like an ES2 but then realized that the ES2 Mk2 was a G80/M18 with Norton badges so that wouldn't fit the bill either.
My only other suggestion would be the "unified twin" - did that have an external feed to the rockers via the return oil line? But then it was only a prototype so I doubt that many oil tanks would have been produced for it.
Quite a mystery!

Yes very strange, although the tanks on G15 (CS Etc) differ from most late rounded tanks as they also have the spigot (arrowed) for the crankcase breather pipe.

Yes, both of our G15s ('65 & '68) have this spigot. I looked at eBay as you suggested and all the tanks listed, except those made in India, are from the USA. The one from Denmark says in the blurb that it too originally came from a dealer in the USA so perhaps this is a clue? Could it be a chain oiler for hard ridden desert sleds? Maybe one of our North American members can shed some light?

Ahh, maybe. Seems most likely.
Pic from 1956 manual, pipe from tank breather used as chain oiler