Dating the bikes

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marshg246 said:
The first 20xxxx number I have is 200623: According to the factory record, this was the 1st built on Dec 9, 1971 and it was a blue roadster. It was sent to Challenge Motors, Barcelona Spain Nov 21, 1972
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Yes, that's my Commando and the 52nd machine of the day before, 8th December 1971, 150*** came of the line.
 
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The frame no 159485 is stamped on the head stock.
There is no plate etc.
 
Wherebouts in Australia are you? If you have some idea where the bike lived you may be able to get some clarity around the engine number by talking to the local police or registration office, as I'm pretty sure that the new engine number is a police issued number and they may have records. Whichever way you look at the bike it'll always be something of an orphan, so I'd be careful to not spend too much money on it and just enjoy it. It's perhaps odd that so much of an old bike's value is determined by the numbers, but that's the way it is. ere's an interesting Aussie article from Phil at Union Jack Motorcycles. https://www.unionjack.com.au/blogs/...rs-clubs-registration-authorities-and-wankers
 
Looking at Phil's article it looks like your new engine number (starting with an "N" was a NSW Police number.
 
Good article.
My brother-in-law had the bike since 1975ish.
I’ll take a run up to the motor registry and see what they have to say.
 
nopdog said:
Good article.
My brother-in-law had the bike since 1975ish.
I’ll take a run up to the motor registry and see what they have to say.
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nopdog - if you are asking advice on dating a bike - man!! you need to get out and about a bit more.
 
Yes, I hear you!!
But just need to know for rego.
It will be on classic rego so it’s not a real biggie.
 
nopdog said:
Yes, I hear you!!
But just need to know for rego.
It will be on classic rego so it’s not a real biggie.
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Already answered, the 159 number does not exist as the 1971 bikes did no go that high.
How it got that number who knows, compare the font to the attached picture of my bike.

As posted the 20M3S prefix was moved (from in the concave curve near the front as below) to that location on your bike somewhere around mid 1971 ish.
That can not be disputed.
1971 was the end of the line for the 20M3S engine with the camshaft case breather (the fitting and hose back to the oil tank)
The 1972 spec 200 series engine is all but a new ball game and different in many ways and easy to spot.

Here is my March 1971 stamped 750 Fastback which has the earlier 20M3S / number location.

20.JPG
 
If that number is real (the font looks off but might be the picture) and 150xxx it would date around September 1971 based off the GM list.

There is also a possibility the N number would be on record.
 
Then there is the s/n on the gearbox upper bolt casting that should be looked at. It should match engine s/n and a bit harder to change due to location. Only matters with the Commando, numbers won't match on your earlier Nortons
Oh and btw, nice exhaust. Tucked in exhaust pipes as original for '71 and looks to be genuine Dunstall silencers....
Side reflectors on tail light don't look '71, more like '70
 
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Can’t find it as I don’t really know where to look.
The frame no is stamped into the headstock.
 
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