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https://www.britbike.com/forums/ubbthreads.php/topics/867928#Post867928

Were there engines that outwardly resembled a Combat engine produced after production number 211110?

http://www.gregmarsh.com/mc/Norton/CommandoID.aspx

"In truth, the high-performance engines were still sold even into 1973, but they were not called Combat and they did not use the Combat (2S) camshaft. See: N3/23 for the various compression ratios available." GME


Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project
1971 BSA A65 650 - Project
1972 Norton Commando 750 "Combat"


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Originally Posted by Jon W. Whitley
Were there engines that outwardly resembled a Combat engine produced after production number 211110?

Depends what you are referring to as all Commandos tend to have a narrower gap between the barrel and head fins including the 850 models just not as narrow as the Combat engine or the post-Combat RH6 'High compression' head (but not as high as the Combat).

Post-Combat 750 models with the RH5 (standard/"Low" comp. head) or RH6 ("High" comp. head) still had 32mm carbs and the disc brake except for the Hi-Rider and all had the rear crankcase breather.

I believe the Combat cylinder head could have been available (to special order?) after the Combat series ended but no specific Combat parts are listed in the parts book from 212278 (750).
http://www.classicbike.biz/Norton/Parts/1970s/Commando_Parts_73-74.pdf

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Combat is a controversial term in some norton circles.
I have long call 200000 series as 750 combat "BREATHER"! However....
Without the combat 32mm port High Compression -.040" head /carbs and cam it is NOT high performance combat TUNE.
There are other intermediate evolutionary changes during the 200000 series that most people are not aware of...but more important
I own 4ea 200000 series engines 2 full blown combat and 2 combat breather post 212278.

While Greg seems to be a nice guy, I have little enthusiasm for his data gathering results.
.

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Why would you call it a "Combat breather' when it appeared pre-Combat ????
ALL the 1972's had it ?

-----------------------------------------------------------------------------------------------------------------

Nortons offered all sorts of performance options from the late 1950s even.
Port and polish, bigger valves, twin carb options, hi-comp pistons.
Swept back pipes. Blah de blah de blah.
As did various Dealers.

This seems to have continued almost to the present day even.
Any bike at the present moment could be anything of these 'improvements',
they don't necessarily have come out of the factory like that.
A lot can have happened in 40 or 50 years ...

Its also worth commenting that Norton Villiers published two tuning leaflets in 1973
to enable owners to make an 850 into effectively a 'Combat' model, in 2 stages.
This was based on the Rawlins & Baker factory 850 hotrod that was clocked at Elvington
airfield speed meet at 142 mph.
Dennis Poore was said to have wanted to sell these as a factory model.
But for whatever reason - warranty claims* ??!! - this was not done.
*The Combat fiasco ... !

The 'prototype' factory 850 'Combat' model, Rawlins (rider) and Baker (engineer) in attendance.
Except it used the 4S cam, not the 2S so wasn't strictly a Combat anyway.
Pic courtesy of Andover Norton
https://andover-norton.co.uk/img/imagescaler/5a/5a20f9cd03c2cfc8932816729bb7d125.jpg
Motorcycle Mechanics - and other mags - ran some detailed articles on this bike, circa 1973.
Which really pushed the Combats and subsequent models into the limelight.
Which is wandering from this post, but somewhat relevant...

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I have an 8/72 build 750 211223. When I tore it down I found:
Standard compression head that has no stamps, not sure what the actual ratio is, but it is definitely not shaved like C stamp ones I've seen
standard camshaft, no markings, not a 2s
superblend bearings
rear breather
32mm carbs
disc brake
It must have been a hold over that was sold in spring 1973 as it has a 1973 title but it is in the 72 vin range.

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Thats good info. (but a lot of numbers !?)

Now, reportedly, a number of Combats were reworked to not be Combats, sometime late 1972 ?
We wonder if yours was one of those - with superblend bearings.
Or was simply one of the ones that was initially not a Combat anyway, as the spec that was to be used into 1973.

Or could have had anything done to it, if you were not the 1st owner....

Do you recall what version of 'superblends' it had ?
There were a few varieties - before Nortons standardized on the FAG 306E
Particularly in the 850 models.

I have a story of those 'superblends'
I bought a magazine with the story of that combatted 850 hotrod.
I bought a basketcase 850 engine, with the intention of doing just that.
And approached the local Norton Dealer, the biggest here, for a pair of replacement said superblends.
They trotted out a pair of NJ306 bearings. (as the dommies used)
I asked about the 306E.
Nope, they insisted these were just as good.
Hmmm, combat history hadn't spread to all corners of the globe ...
(the E stands for Extra - load capacity)

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Originally Posted by htown70
I have an 8/72 build 750 2211223.

211223 (2211223 has one too many digits)?

Originally Posted by htown70
superblend bearings

According to factory Service Release N.2/9, the R&M (later RHP) 6/MRJA30 bearing designated "Superblend" was fitted from engine number 211891. If the bearings you found were the later FAG NJ306E that also inherited the Superblend name then they are likely to have been replacements for the standard MRJA30 roller bearings as the FAG Superblends were not introduced until around January '73 according to Service Release N2/10.

https://www.nortonownersclub.org/sites/default/files/Main-Bearings-v1.1.compressed.pdf

Originally Posted by htown70
It must have been a hold over that was sold in spring 1973 as it has a 1973 title but it is in the 72 vin range.

The 8/72 date stamp doesn't necessarily indicate the bike left the factory during August '72 and would have taken several weeks to get from the factory to the importer and then be sent on to the dealer before it made it onto the showroom floor.

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My 72 built Combat was not registered until 1974, after the news got around about all the issues with the 72's and all the 2ing and froing of warranty work even whilst still in the crate, it could have been hidden away in the back of a workshop or showroom for months.

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sorry 211223, don't remember the bearing number but they were FAG, but it didn't look like the bottom end had been apart, today she's a running rider

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Originally Posted by Jon W. Whitley
Were there engines that outwardly resembled a Combat engine produced after production number 211110?

The first Commando I rode (around 1979 iirc) was a just restored black 1972 750 Roadster. (with a Combat spec engine from new)

imo only.
There is no such thing as a Combat engine.
Afaik the engine in the 1972 and 1973 Commando's was the same thing with the revised for 1972 (over the previous 20M3S) engine cases with rear breather.
That engine for a period could be bought with the added Combat spec.

Why folk identify Combat with the breather is beyond me.
#
I had for whatever reason incorrectly taken for granted the 1973 750 Commando was based on the 850 type cases and through bolt type cylinder not a rehash of the 1972 bike.

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"That engine (20M3S) for a period could be bought with the added Combat spec."

On occasion I hear this claim, without any convincing evidence, "the factory" produced 20M3S with all norton factory combat tune components.

A 71 (20M3S) Commando with the dunstall hot rod R2 cam and other similar components would be extremely similar. That is all I have found so far....

200000 series case engines built 71, 72 and 73


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Don't know about 'Combat spec', but there was (extensive ?) discussion on the NOC Forum that Nortons
offered engine tuning services for some years prior to the Combat versions appearing.

(But there was no use of that 'Combat' moniker until they appeared for the 1972 model year ?).

The race shop at Thruxton airfield was building Production Racers (for sale) for some years before the Combat spec appeared for 1972, so its not like they didn't know how to make a Commando go.
One won the Thruxton 500 mile race in 1970.
Note the pre-peashooter mufflers
https://images.squarespace-cdn.com/...ommando+Production+Racer+road+test+1.jpg

More HP than a Combat, available years earlier, and with no main bearing problems. !? (the yellow ones).
(The blue ones are the Factory John Player team racers.)
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"Don't know about 'Combat spec',"

Then why are you running the topic off the rails?

Is this not quite simple? What the factory hot rod shop or Dunstall or any aftermarket shop that builds "specials" is not the discussion at hand.

At least to me, the discussion is, what did the factory build as a specification for a standard "production" model.
Use of 20M3S then transition to 200000 cases then to 300000 cases has little to do with "combat tune" as a "factory" production specification for a period of the partial Model Year 72 750 Commando.

There persists an allegation that Norton Factory marketing and production made Combat Tune Commando's as a publicly marketed item.
All I ask for is some scrap of evidence it was something the factory built WITHOUT a individual request prior to the machine being built.


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Well, those 750's WERE sold post-Combats as varying compression versions, via the list of RH heads.
Without a 2S cam - does that make them Combats or not ??
I think GregM is taking it too far to call them Combats.

You could buy a Production Racer, off the showroom floor, for some years prior to the Combats.
This is not 'running it off the rails' at all, merely pointing out reality !!
That CERTAINLY means that performance engines were available prior to the Combats, for some years.
When, precisely, did this arrangement end. ??

And, all the PR parts are in the parts lists, to DIY.
So a Dealer could have done something for a customer if they requested it.
With factory parts...

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Originally Posted by Rohan
snip
Without a 2S cam - does that make them Combats or not ??
I think GregM is taking it too far to call them Combats.

"Combat cases" is all 200000 cases, and were used in "standard tune(with RH1)", "combat tune", "std +RH5", and "std + RH6".
"Combat tune" is exactly that set of components as apparently only some folks know....Greg excluded IMO
No one must accept to use my terminology, but the distinction I do make is IMO irrefutable.

I'm still waiting to be convinced that "combat tune" engine was full factory, non special, production version with 20M3S cases.
Combats were built in 71 even higher than 202xxx were Dec 71 on the VIN plate.


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In the Feb 70 Norton sales price list was a Combat option which cost £56 14s and 10p.

Doubt it was the 72 Combat tune but was whatever the PR shop had as its engine tune at the time.

Source Norton Twins Roy Bacon pub 1981

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Thanks K, that does ring some bells.
Was mentioned in a previous discussion on Combats when I think back.
Be interesting to get some detail of what all those quids got you as a Combat engine then.

The Proddy Racer is listed as having the 3S cam, at some point in its life.
Wonder who did all those cams, and cylinder head iterations ?
1S 2S 3S 4S 7s RH1 RH4 RH5 etc etc
Don't think I've seen an account of who did what and when. And why ...
Wonder if its too late to find out ?

So, do we have an inkling/magazine article of/on the race shop at Thruxton airfield anyplace perchance ?
Sure to have been a magazine article or 2 ??
Norman White is still there ? - same shop ??

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