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DotKomradeThu Jun-07-07 05:10 AM
Member since Mar 18th 2009
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"1958/1959 Dominator 99 query"


  

          

Hi,

A friend and I are about to invest in a Norton Dominator 99. We are in South Africa where these kinds of things aren't easy to come by, so we're pretty excited, but just looking for a bit of extra information about the bike...

The bike is represented as having twin carbs, and a sports mag (I take it this refers to the magneto) as well as matching numbers.. It was modified at some point in its past to be a café racer, hence the pipes and attachment at the rear, but hasn't been ridden or worked on by the current or previous owners. The seller claims that it is a dominator 99S (not SS) but I'm sure he's mistaken. In any case, I don't see many photos of twin carb domis so I'm still trying to figure out what exactly the story is with this bike. Apparently it was built in December of 1958 and sold as a 1959 model. This seems to be right based on the engine number which is (if it isn't clear in the pic) 80436. The bike comes with several boxes of parts ordered through the Norton Owners Club in the UK (which can be seen still unopened in the background), and frame wise is complete (mudguards, tank, badges, pedals etc). He has never dismantled the engine, so we have no idea what we'll find in there...

So my few questions are:

1. What is the story with this twin carb model?
2. As I stupidly forgot to check when I was looking at it last weekend, where exactly is the frame number located, and should it be on some kind of plate or stamped into the frame?
3. Is there anything specific that we should look for or at on the bike?
4. Is it safe to turn the engine over, using kickstart or wheel, assuming it hasn't been started in a number of years? Just to check whether the pistons are free I suppose..
5. Anything else I should be aware of?

Thanks. We haven't even got round to checking books, manuals etc yet, so I don't really have that much info on the model yet, but anything you can tell me will be invaluable.

Thanking you in advance.

Matthew Tapson.

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

  

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DotKomradeThu Jun-07-07 05:18 AM
Member since Mar 18th 2009
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#1. "Another pic"
In response to Reply # 0


  

          

Some more pictures...

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

  

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johnandnzSun Jun-10-07 07:13 PM
Member since Mar 18th 2009
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#2. "RE: Another pic"
In response to Reply # 1


  

          

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.

  

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johnandnzMon Jun-11-07 12:31 AM
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#3. "RE: Another pic"
In response to Reply # 2


  

          

Take a look in here

http://www.nortonownersclub.org/

  

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johnandnzMon Jun-11-07 12:36 AM
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#4. "RE: Another pic"
In response to Reply # 3


  

          

This is what it could look like

Attachment #1, (gif file)

  

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DotKomradeTue Jun-12-07 03:50 AM
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#5. "RE: Another pic"
In response to Reply # 4


  

          

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.

  

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johnandnzTue Jun-12-07 05:25 PM
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#6. "RE: Another pic"
In response to Reply # 5


  

          

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.

  

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johnandnzSun Jul-29-07 07:10 PM
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#7. "RE: 1958/1959 Dominator 99 query"
In response to Reply # 0


  

          

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

  

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