1971 Owners Poll

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Deckard

Deckard

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Well, it's rainy and boring today. I've noticed that sometime in the spring of 1971 that the engine case serial number moved from the front of the drive side case to the side. Just wondering when that occurred. Mine was built in May. So, it was prior to s/n 1483XX. It would also be interesting to hear any trivia about why that was done.
 
My 71 has the numbers stamped on the left side just below the barrel. It is 150649 What is the 20M3S right in front of it designate?
 
MikeM said:
What is the 20M3S right in front of it designate?
Click to expand...

20M3 is the Norton model code for the early Commando = Atlas(20) Mk3 as the Commando was supposedly going to be called 'Atlas Mk3'.
'S' designates a camshaft drive points engine as initially fitted to the S type, but later adopted for all models.
The 20M3S stamp was finally dropped at the end of 1971.
 
MikeM said:
My 71 has the numbers stamped on the left side just below the barrel. It is 150649 What is the 20M3S right in front of it designate?
Click to expand...

Mine are also on the left side under the cylinders...and mine came off the line 238 bikes later than yours. Anyone know what the average daily output was?
 
MikeG said:
Anyone know what the average daily output was?
Click to expand...

Probably about 40 per working day (or 200 per week assuming a 5 day week and based on approx. 48 working weeks in the year or 50 weeks if there was no 'summer shutdown' by then?) going by the published production numbers for 1971, 141000 - 150500, although I've had a suspicion for a while that 150500 is a misprint perhaps should be 153500 so it could have been about 50 per day.

As for the change of engine number stamp location, it seems to have occurred sometime around 145xxx.
 
I have 20M3S 1451xx and is stamped on the side. I wonder if there are any earlier..
 
I'll go check my 71 when I get home and report back. Just have to shuffle the 72 and 73 out of the way. First world problems
 
I did a net check for 1971 Commando engine photos. 143958 is forward above the breather outlet. 146666 is mid crankcase. Somewhere between these was the change.
 
I must have the cuckoo in the nest first registered in May 1971 frame number 1367## engine number 20M3/1309## . When I bought the "bike" it was a conglomeration of knackered parts and advertised as a LR Fastback with no rear cowl. However it did hide a suspicious amount of white paint on the side panel and oil tank and I thought at the time maybe the strange registration date on the V5 compared to the non matching frame and engine numbers had something to do with it being possibly an Interpol police motorcycle. But is certainly a bit of an anomaly and only that.

Jg
 
As far as I can tell I'm the third owner of my 71. I bought it off my Brother in law 24 years ago and he bought it used on April 12 1973 from a Norton dealer and her number is 143440.

Mark
 
Hmm, it looks like L.A.B.'s on with the change being around s/n 145XXX. I wonder if we have any members with s/n's in the 144000 thru 144999 range that could weigh in about their engine case s/n location. It would be interesting if the change occurred at some odd number before 145000 or afterward. It might even make your 750 a trivia item :)
 
My 71 is a tangerine SS model and went to Berliner Corp U.S.A. on the 4th June 1971 20M3S 145243 the numbers stamped on the left side just below the barrel. Hope this is :D some help. Harold.
 
In my list of Norton VIN's I have 145275 as having the engine number stamped mid-way on the side of the case.
So the change came somewhere between the SS model of 'slideways' VIN 145243 and 145275
 
Your're right clanger. We're getting closer with owners weighing in with 145XXX s/n's verifying the change around then. It still would be nice to here from anyone with a 144XXX s/n.
 
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