Horn ???

[Brandis]

Since I have never seen a complete A7, and the Google Images are confusing, can someone post a photo of what size and where the horn goes?     The only drawing I have of the very early bike with the 'pogo' center stand has a small horn under the oil tank. I assume there's no chance to find one of them.  So I have two big classic Lucas horns but they seem too big for anywhere around the front of the engine.  I assume the smaller diameter Lucas horns are a later model.

Besides that, dyno and exhaust coming from the UK.   Auto advance from Oz.  Remaining head bolts from Canada. 
Long Live the Commonwealth !!

[trevinoz]

The horn is a Lucas HF1234 and hangs down behind the battery box. It has a straight bracket.

[Greybeard]

I've seen a much more compact horn for the early bikes. My hooter is mounted on the drive side saddle lug.

[trevinoz]

There are pictures around showing possibly a Lucas HF1140 but the Lucas parts book doesn't list it for the A7.
The correct mounting point is below the near side (left) saddle spring.
I think that the illustrations with the different horn were pre-production.
The HF1234 used is the first type of this horn which was first produced in about 1937. This one went to 1948 when the body was changed for 1949 and then again in 1950. The last type came in about 1952.

[Brandis]

Big one under the seat spring it is.   In this part of the world,  who's gonna know?

[Black Sheep]

1951 Star Twin showing Altette horn mounting.

[Greybeard]

Just for fun I bring you this picture. That's not me by the way.

To explain; the owner has changed the boring standard horn for one of the old style ones.