Some more pictures...

Attachment #1, (jpg file)
Attachment #2, (jpg file)

Sorry to say but the photo of the head shows this bike was not originally fitted with twin carbs. Twin carbs came with the SS head and this bike does not have an SS head. One of the easy ways to tell is that an SS head has the carb studs fitted at 3 oclock and 9 oclock not the 12 and 6 oclock on this head. There were no SS models in 1959. The twin manifold on this bike is an after market or home built item.

This carbs fitted are also concentrics. Originally they were monoblocs.

The frame noes should be on the gusset plate on the left hand side above the swinging arm.

Still a 99 is a good bike. One issue with the 600 is that if the barrel has been rebored there can be little metal remaining and high compression is not a good idea. You can blow the barrels off.

Take a look in here

http://www.nortonownersclub.org/

This is what it could look like

Attachment #1, (gif file)

Hi,

Thanks for the advice. I thought the 2 carb setup was odd... Another question: What exactly is the difference between a monobloc and concentric carb?

Thanks.

Matt.

If you go to this site and look at Amal you will see photos of both concentric and monobloc carbs.

http://www.hitchcocksmotorcycles.com/

One of the main differences is that on the concentric the main jet is located centred to the float hence concentric. On the monobloc the float chamber is located to one side of the carb. Both carbs are avaiable left and right handed and the monobloc can also have a shortened "chopped" chamber for use on the left hand side of a pair.

Monobloc carbs were standard through the 1950s and early 60s and replaced by Concentrics in the mid 60s. Concentrics came in mainly for cost reasons. They are cheaper and many people do not consider them as good as monoblocs. However they are smaller and fit on twins and triples where it would be hard or impossible to install three monoblocs.

The 99 would have one monobloc as standard.

Hi Matthew,

I owe you an apology.

I have just been reading Mick Walker's Norton Dominator book and found that according to him from the 1959 year twin carbs were avaiable as an optional extra for 7 pounds 12 shillings and 2 pence on the 88 and 99. No pictures so I don't know what the manifold looked like. This is definitly pre the down draught SS head so perhaps the bike you are looking at could have had twin carbs (monoblocs) from day one.

This was a surprise to me and I hope my earlier posting has not steered you wrong.

Regards

John