850 Mk2 & Mk2A Discussion Split From Another Thread

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marshg246 said:
I've heard the RH4/RH10 thing before but have never seen factual on it. Do you know of anything to back that up? I would love to add it to the page but I like to keep things as verified as possible on that page.
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Reported in the Jan./Feb. 1974 issue (55) of Roadholder (the UK NOC magazine) p.36:

"COMMANDO 850 MK2A INTERSTATE & ROADSTER
Announced to coincide with the *London show*, the Mk2A version of the 850 Commando sports several improvements on the earlier Mk1A. The only change to the motor is that the ports are tapered to 30mm whilst retaining the 32mm carbs......etc."


*(Presumably the Earl's Court show, this would have been sometime around October/November '73)

"Announced" therefore the Mk2A probably wasn't available to buy at that time.
 
L.A.B, we've gotten way off the OP's topic. Could you split this where the model identification started?

Anyway:

310311, marked Nov 73, has a RH10 (known original and known MK2A)
307542, marked 8/73, had a RH10 (not known if original and now on 320691, 307542 was a parts bike, not "A", used to rebuild 320691)
A 75 MKIII I'm working on has an RH4 head that the owner tells me is original.
 
marshg246 said:
L.A.B, we've gotten way off the OP's topic. Could you split this where the model identification started?
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I will have to take a look at that although it's not as if this subject hasn't cropped up before.

marshg246 said:
A 75 MKIII I'm working on has an RH4 head that the owner tells me is original.
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Yes, the Mk3 apparently reverted to the RH4.
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850 Mk2 & Mk2A Discussion Split From Another Thread
 
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L.A.B. said:
I will have to take a look at that although it's not as if this subject hasn't cropped up before.
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Yes, and as you know, that's why I started the Norton Commando Identification page.

It would be nice to not keep having the half-baked discussion here every few months and this time people are actually participating. Since I am always looking to improve the identification page and since this is the first new thing anyone has brought up since I started it, I would like to encourage people to participate in the discussion.

Of course, it can continue here.
 
maylar said:
Only general consensus and anecdotal evidence. My MKII has an RH10 with 30 mm ports. I can't find any official references to that head, AN doesn't show it. They do show the RH4 with 32 mm ports for 73-74 models.
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So, AN has options for 32mm/32mm (06.2711) and 1-3/16" - 1-1/8" (06.2819) for 72-74. If my math is right, that's 30.1mm/28.6mm. But, I just measured. My RH10 head is 30mm at the manifold and the manifolds are 29.6mm at the head side and 32.1mm at the carb side. I assume the 1-3/16 x 1-1/8 is wrong since they are nominally 30mm x 32mm.

The only printed parts manual I have says that 06.2711 is for 32mm carbs and 06.2819 is for 30mm carbs. No mention of the manifold sizes.

The AN site has both sizes for 72-74, only 06.2711 for 75 and only 06.2819 for 71
 
marshg246 said:
So, AN has options for 32mm/32mm (06.2711) and 1-3/16" - 1-1/8" (06.2819) for 72-74. If my math is right, that's 30.1mm/28.6mm. But, I just measured. My RH10 head is 30mm at the manifold and the manifolds are 29.6mm at the head side and 32.1mm at the carb side. I assume the 1-3/16 x 1-1/8 is wrong since they are nominally 30mm x 32mm.

The only printed parts manual I have says that 06.2711 is for 32mm carbs and 06.2819 is for 30mm carbs. No mention of the manifold sizes.

The AN site has both sizes for 72-74, only 06.2711 for 75 and only 06.2819 for 71
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32-30 is 06-5196.
https://www.obsoletebikeparts.com/a...pacer-inlet-manifold-32-to-30mm-pair-06-5196/

PeterJoe said:
On the cover of the Norton Mk II/IIA Supplemental Parts Book, it states that it covers 850 models, after engine number 307311 therefore I assume that the first Mk II/IIA started with engine number 307312.
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The first thousand-or-so were Mk2s (for the US market).

Mk2A production supposedly started from 308360 (for the European market) with subsequent Mk2s continuing to go to the USA.
The first US Mk2A (not including the JPN) was supposedly 316170 with Mk2s still being sold in the US.
Some Mk2As with serial numbers lower than 316170 got to the US, probably through the popular 'personal export' scheme where bikes could be bought tax-free by non-UK residents, US service personnel, etc. as long as the vehicle was exported within 60 days Edit: [the specified time limit] thereby saving 30-40% on US showroom prices assuming they could get them home cheaply, (possibly shipped home courtesy of Uncle Sam?)
 
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L.A.B
The problem with Norton dating is a few words seems to pop up regularly, suppose, presume and assume with no actual record to back any thing up.
As I already knew and was confirmed those records are lost. (I asked J S)

That link to the website says Mk1a made from Sep73 to Feb74 overlapping Mk2 and Mk2a dates (I think the Jan74 for Mk2/Mk2a is wrong.

How my Dec73 stamped Mk2a got to the USA will never be known unless the original owner is found.

#
Does anyone really believe you could go to a model release (from a company in financial troubles not to mention the Japanese models being released in that time period, CB750/Z1-900/H2750) in the home country in the later part of 1973 and when you went to your Norton dealer on Monday morning be told, come back next year ?

Of course all it needs is someone to post they picked up their brand new, Mk2/Mk2a in late 1973.
 
Time Warp said:
L.A.B
The problem with Norton dating is a few words seems to pop up regularly, suppose, presume and assume with no actual record to back any thing up.
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Correct.

Time Warp said:
That link to the website says Mk1a made from Sep73 to Feb74 overlapping Mk2 and Mk2a dates (I think the Jan74 for Mk2/Mk2a is wrong.
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So, you "think" it's wrong! Possibly it is. It depends on what you mean by "wrong"? As far as I'm aware, nowhere does it say they are production dates.



Time Warp said:
Does anyone really believe you could go to a model release (from a company in financial troubles not to mention the Japanese models being released in that time period, CB750/Z1-900/H2750) in the home country in the later part of 1973 and when you went to your Norton dealer on Monday morning be told, come back next year ?
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Very likely yes, you'd be offered the current model if they had one.
 
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The problem it seems is to much copy/paste and it all being taken as gospel or some other unreliable source and then the hat being made to fit the head.

The same or similar mumbo jumbo is on another well known posters website... I don't think the answer is written inside a manifold or on a Mk3 or RH4 cylinder head ?

It would be nice to know but Norton records were poor compared to Triumph.

My TR6 and the level of information is stunning.
Your bike TR6 05938 was one of 200 USA spec bikes made in that batch.

The engine was built on Thursday 28th feb 1957 with the following specs.
Lucas Auto advance magneto, E3610 (8.5:1 CR) pistons and Tacho (RC109) and USA spec.

The bike was built on Tuesday 5th march 1957 US spec so high Flanders handlebars.

It was dispatched on Wednesday 6th march 1957 to Triumph Corp (east coast).

These specs make it a TR6A model which had low pipes on each side and twin instruments.
Colour would be Aztec Red and ivory.
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Time Warp said:
The problem it seems is to much copy/paste and it all being taken as gospel or some other unreliable source and then the hat being made to fit the head.
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One can only try to make some sense of it from the information available.

Time Warp said:
The same or similar mumbo jumbo is on another well known posters website... I don't think the answer is written inside a manifold or on a Mk3 or RH4 cylinder head ?
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o_O?

Time Warp said:
It would be nice to know but Norton records were poor compared to Triumph.

My TR6 and the level of information is stunning.
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Precisely.
 
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998cc said:
Greg Here is a link to my first thread on Access Norton. This is where it was determined my bike was likely a Mk2.

https://www.accessnorton.com/NortonCommando/new-member-new-to-me-74-commando-mk.26212/#post-391652

~Russ (998cc)
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Russ,

I'm not disputing anything, Even when they were relatively new, parts would get swapped and 40+ years later it's often nearly impossible to know how they started life.

I know the life of my rider because I bought it from the original owner and he kept the MK2A parts he removed and told me how it got to the US, what he changed, and provided a good bit of documentation to prove it. It is a MK2A but a much lower serial number to those 74 MK2As imported directly to the US. Also, there is no doubt that is 310311 but has a 11/73 date on the certification label. In other words, everything about it says 1974 MK2A except the date on the certification label - what does that mean - I have no idea.

So, yours, like mine is a MK2 (or MK2A) number but the certification label is two months earlier than mine. If I were going by that date, I would say MK1 but the serial is generally accepted to be MK2.

Mine has an RH10 head. What does your have?
 
Time Warp said:
The problem it seems is to much copy/paste and it all being taken as gospel or some other unreliable source and then the hat being made to fit the head.

The same or similar mumbo jumbo is on another well known posters website... I don't think the answer is written inside a manifold or on a Mk3 or RH4 cylinder head ?

It would be nice to know but Norton records were poor compared to Triumph.

My TR6 and the level of information is stunning.
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Please take nothing as gospel on my site and please read the first 2-3 sentences. I have every book on Norton I can find and I've had the page checked by a few people who certainly know more than me on the subject. Please, if you have any factual info, provide it. I'm trying to provide a free service to the community and the last thing I want to provide is misinformation.

The only way I know that this could ever be greatly improved is if every member provided info on their bikes and made it clear when that info was known correct.

You are correct - as long as you understand Triumph model years and in later years, their model designation, there is little confusion. It took me a long time to get it through my thick skull that Norton had no such system. A big Duh moment was when L.A.B told me that there was no such thing as a MK1 until there was a MK2. I just assumed that MK1 was assigned by Norton as the first iteration.
 
My 3077.. has a RH10 Head. In the box of original bits was a Ham Can air cleaner, non baffled.

I had a previous Mark II that was 31???? Don't recall all the numbers.
Had a RH10 head with a baffled Ham Can.
 
MichaelB said:
My 3077.. has a RH10 Head. In the box of original bits was a Ham Can air cleaner, non baffled.

I had a previous Mark II that was 31???? Don't recall all the numbers.
Had a RH10 head with a baffled Ham Can.
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So, MK2 but with a very early certification label date. Your 3077xx 9/73; my 310311 11/73 both with RH10 heads.

The part book supplement says: After 307311, Copyright 1974, MK2/MK2A. It does not say that 307311 (or 307312) was the first "1974" bike or that that number started 1974. So, it might well be that all the book writers assumed that it meant something it didn't.

Now I would like to know the lowest serial number of a bike with a RH10 head and what the date says on the certification label and how confident that it is original info.

Similarly the highest serial number of a right shift bike with a RH4 head and the certification label date.
 
Whats does the date stamp have to do with anything ?

The problem I see is some book (And I was the one who queried that in the other thread that this one came from) said Mk2/Mk2a had a Start date of Jan74 but we know as a fact that is not true, our bikes prove it and there is no current documentation to disprove it.

I do not think there was a "1974" Mk2 or a 1973 Mk1 for that matter, just production of a model until it was superseded and production stopped and the next model was commenced (even if it was all but the same bike)

Is my Mk2a with a Dec73 tag a 1974 or 1973 , no it is simply a Mk2a designated model until the Mk3 was produced.
Why that book ? stated that month of Jan74 is unknown unless you could ask the person or source firsthand (I will presume that is not possible)

Why that book or source also stated Mk1a production was overlapped with Mk2a production is no different, be it misinformed or speculation at the time.
It says Mk1a production was very short but overlapped the start of Mk2 (including the near same bike Mk2a) by one month ?
Does that mean there are Mk1a's with Mk1 engine numbers with Jan74 / Feb74 tags to go along with the proven here Sep73/Oct73/Nov73/Dec73 Mk2a's ?


850 Roadster 1A Sep-73 Feb-74

850 Roadster 2/2A Jan-74 Feb-75.

Is that not a red flag ?
There is simply things that are lost in time, other that can be overthought.

Of course when asked I say that is my 1974 Mk2a... Dec73 tag or not.
 
The kicker with the stated Jan74 start, do you leave it, change it, don't worry about it ? Can you dispel it, confirm it to be true incorrect or otherwise.

To do so even with the facts based off real motorcycles in this thread might be deemed history changing for those who read it in the future and it all could have started by information misheard, a column misread or simply some other glitch.. be it true,false or half way between.
 
Time Warp said:
The kicker with the stated Jan74 start, do you leave it, change it, don't worry about it ? Can you dispel it, confirm it to be true incorrect or otherwise.

To do so even with the facts based off real motorcycles in this thread might be deemed history changing for those who read it in the future and it all could have started by information misheard, a column misread or simply some other glitch.. be it true,false or half way between.
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The only thing I can tell you is that the last time that pageswas updated was 11/29/2019 and it has been visited 6404 times (1606 distinct people). No one has provided any update/complaint/question. I've been as clear as I can that it is an attempt to provide info that it is clear that people want.

The 3rd table, where you're taking issue has no red flag. It gives possible ranges based up lots of conflicting info. Maybe I need to make that more clear, but this discussion over the past couple of days, and in fact your statements, show that depending on how you look at it, those ranges are correct.

Now that several have shown that they have MK2 serial numbers with certification labels showing much earlier than Jan 74, maybe I need to make it even more confusing and move that date back.

BTW, that table closely matches the one in the sticky forum of Commando Information that has been present here for a very long time.
 
marshg246 said:
BTW, that table closely matches the one in the sticky forum of Commando Information that has been present here for a very long time.
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Yes I have seen it, mentioned it in public and it was dismissed.
It is a copy/paste of the info you have.

At least you actually have a Mk2a and of course thank you for the time and effort put into your resource/website, wonky dates excluded.

I am not even going to respond to the Mk1a silliness to Feb74 given it is proven that Mk2's/Mk2a's go back to September of 1973.
Or maybe Norton management was that out of control.

Keep up the good work.

Mk2a 311032 built December 1973, purchased out of Pennsylvania.

850 Mk2 & Mk2A Discussion Split From Another Thread


1971 750 Fastback 20M3S/143958 built March 1971, purchased out of Washington state.

850 Mk2 & Mk2A Discussion Split From Another Thread
 
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