50 Years of Norton Design: Interview with Brian Slark and Mick Ofield

They both promote the myth that the 750 was light and fast while MK3 was very heavy and slow.
I just weighed the MK3 and an Alton equipped 750 with the same scale. The difference was negligible, 5 pounds.
That's not going to slow things down by a measureable amount.
Then we ran the two bikes under full acceleration from about 10 mph to 110 mph. The 750 was given a head start which should allow it to romp away, but it did not until about 80 mph, where it pulled away slowly .
This particular 750 has some added oomph in the form of performance cam, bumped compression and a Comstock ported head including the D exhaust port modification. It is considerably faster than a stock 750.
The MK3 engine is stock and still runs all the same internals it had when it left the factory 47 years ago.

I think if we run the bikes again with the MK3 given the same lead this time, it will pull away over the whole distance.

So I guess it's the old thing where if something is stated enough times it becomes truth.

Glen
 
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The old hot-rodder's addage was "There's no substitute for cubic inches." That might apply here as well. You either run the pump faster or get a bigger pump to move more fluid. On a side note, one day at the Bonneville Salt Flats speed week I saw painted on the door of a fancy Perterbilt tow vehicle, "There's no substitute for cubic money."
 
jan nelder said:
Deming and the methods he introduced to Japan after WW2 around quality control were crucial to improvements in their industry. I doubt if many UK firms even now know much about some of those ideas, let alone implement them.
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There was a book about Demming and his efforts to get American industry to adopt his methods. I read it a couple decades ago. I doubt it's still in print. The thought that stuck in my head was that he was successful in getting the Japanese to adopt his methods and by the mid-sixties they were producing quality motorbikes, pushbikes, audio gear, TVs and by the late sixties cars. It's worth noting that they were producing cars the market wanted rather than bloated turnpike cruisers. Remember the Datsun 510? Zenith, the last American TV producer lasted another twenty years but are now long gone. The demise of American consumer-goods manufacturing is a sad tale indeed and has led to profound political changes too.

In all fairness to the British and even the Americans, after WWII Japan's industrial capacity was rebuilt with modern tools and equipment under the Marshall Plan. The blast-furnace engines at Blist's Hill on the UK's river Severn were finally retired in 1956 according to the sign. They had been built in the 1830s as I recall.
 
NPeteN said:
No replacement for displacement
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There's no huge difference in relative performance of the various models, unless the dreaded Blackcaps are fitted.
That's where all of the power went. All MK3s were fitted with them so I guess it's fair to say that all MK3s were sluggish in completely stock, quiet form.
It looks like all 3 Commandos on display are fitted with the black caps. This will be just fine for static display.

The Black Cap problem doesn't get mention, they are perhaps unaware of just how bad they are. Lack of performance is blamed on weight which isn't there and also other nebulous things.

I'm trying to stamp out the myth, was hoping these experienced fellows would not promulgate it!

Glen
 
Glen, your Dyno hill and roll on tests are great for showing a modern day perspective on the 750/850 debate.

Why do I say ‘modern perspective’? Fact is when these bikes were in the showroom the mk3 had black caps that killed performance and an electric start which added weight.

So, compared to an earlier 750 they simply were quieter, heavier, slower.

That’s not really a myth is it? They are facts.

They’re looking at the bikes through the lense of the time, whereas you’re looking at them 50 years later, with many inevitable / popular changes and modifications.

I’d suggest you’re both right. No stamping out needed !
 
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To me it's a myth that is being perpetrated. The fellows in the video dismissed the MK3 as heavy and slow compared to the early bike. The only change needed to make the MK3 outperform the early bike is to install those early type silencers, or any non restrictive silencers. So what we are talking about is a 20 minute job and now it will get up and go.
They ( and many others) make it sound like the bike is hopelessly detuned and weighs a ton.
I had a Norton expert in my shop a few years ago. He marched me over to the MK3 and railed at Norton for building the MK3 and detuning it so badly.
When I asked how they detuned it, he had no real answer other than " they dropped the compression way down"
Right, from 8.9 to 8.5, for all 850s not just the MK3 .
That might cost the 850 half a horsepower. I think it can more than make that up with displacement.

Glen
 
Did I miss the bit where the guys in the video mentioned the detuning ?

You seem to have missed my point:
If you take a STOCK mk3 and put it against an early STOCK 750 it is going to be slower and heavier. It’s also going to be quieter, which makes it feel slower to many.

So unless I missed something (not implausible) the gents in the video, speaking about the facts of the day, are correct.
 
They could mention that all you have to do to get performance back is remove the black caps.
And that the weight is only about 30 lbs, the weight of an e start.
They single out the MK3 as being slow but any earlier 850 model fitted with those silencers will also be dead gutless. The MK3 part isnt the problem.

Glen
 
worntorn said:
To me it's a myth that is being perpetrated. The fellows in the video dismissed the MK3 as heavy and slow compared to the early bike. The only change needed to make the MK3 outperform the early bike is to install those early type silencers, or any non restrictive silencers. So what we are talking about is a 20 minute job and now it will get up and go.
They ( and many others) make it sound like the bike is hopelessly detuned and weighs a ton.
I had a Norton expert in my shop a few years ago. He marched me over to the MK3 and railed at Norton for building the MK3 and detuning it so badly.
When I asked how they detuned it, he had no real answer other than " they dropped the compression way down"
Right, from 8.9 to 8.5, for all 850s not just the MK3 .
That might cost the 850 half a horsepower. I think it can more than make that up with displacement.

Glen
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With due respect to these gentlemen - one was a stylist and the other not central to Norton performance - so it's a bit unfair to expect a "what went wrong" revelation wrt Mk3.
Neither of them would have actually been privy to the larger decisions being made either.
 
worntorn said:
They could mention that all you have to do to get performance back is remove the black caps.
And that the weight is only about 30 lbs, the weight of an e start.
They single out the MK3 as being slow but any earlier 850 model fitted with those silencers will also be dead gutless. The MK3 part isnt the problem.

Glen
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Yes they could have said all that.
But from my perspective I’m struggling as to why they should have been expected to talk about what could have been, how the bikes could be modified, etc.
They are just telling us how it was!
 
Deckard said:
Yes, an interesting conversation with principles of the Commando era history. As an American Navy service veteran in 1971, I was all in on a Commando for $1430, with shipping to US for $100. Still own it today.
To those who have not been to the Barber museum, there's a track next to it where they have races and track days.
It sounds like a brand track day was going on during this recording, just wondering what brand, 'cause the engine
noise was very distinctive.
I was there while it was a Porsche track day and there was a Cobra in the mix. It was far more enjoyable to hear the Cobra come by at full throttle. American V8's, I guess :cool:
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Interview likely happened at the recent Barber Vintage Fest. AHRMA racing all that weekend. Brian Slark was Grand Marshall for the 17th BVF which took place last month.
 
robs ss said:
With due respect to these gentlemen - one was a stylist and the other not central to Norton performance - so it's a bit unfair to expect a "what went wrong" revelation wrt Mk3.
Neither of them would have actually been privy to the larger decisions being made either.
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This is correct- important decisions were left to bean-counters and corporate wonks rather than the core of enthusiasts like Slark and Olfield who had actual fingers on the pulse of the buying public. Everyone knows what caused the demise of the industry in GB.
 
Danno said:
This is correct- important decisions were left to bean-counters and corporate wonks rather than the core of enthusiasts like Slark and Olfield who had actual fingers on the pulse of the buying public. Everyone knows what caused the demise of the industry in GB.
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I get your point. But it wasn’t bean counters that wanted to fit e start or black caps!

The customers wanted e start.

I don’t think anyone actually wanted black caps !
 
Fast Eddie said:
I get your point. But it wasn’t bean counters that wanted to fit e start or black caps!

The customers wanted e start.

I don’t think anyone actually wanted black caps !
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It was bean counters who forced the design and engineering teams to keep remaking the same 25 bhp 500cc twin into something continually better rather than move into the modern world with new products. This is somewhat akin to Harley Davidson continually re-engineering their ancient design to keep it reliable enough to sell to their "traditional" customers, who would be offended by anything even appearing "new". Their last foray into "new" was the V-Rod, a good machine that was almost universally panned by Harley types. H-D is doing it's level best to prevent a repeat.

I went to the closest Harley dealer at the behest of a friend who manages their parts department, ostensibly to test ride the new Pan American. The dealership had invited all their customers to come in to test it and the event turned into a game of musical chairs as the same 7 or 8 guys swapped from one saddle to another. After waiting for two hours, I left. The dealer was not interested in new customers at all, only in convincing the old heads that this "new" thing would help keep them in Screamin' Beagle chromed barges for the foreseeable future.
 
Mick appears to hold the same view that Alan mentioned awhile ago- that the MK3 was a changed bike with great loss of performance.
The big loss of performance came with Mk1a and Mk2a models that were fitted with black caps.
I have an original road test of one of those bikes. It is slower through the quarter mile than a BSA A10 , and that is pretty slow!
It is quite possible that these fellows are not aware of how the black cap silencers destroyed the performance of any Commando they were clamped on to.
The official word from Norton was that they were Scientifically designed to offer quiet running without power loss. Nothing could be further from the truth.
It's a strange situation, the Norton twin engine was developed from 25 HP to 60 over about 20 years. Doug Hele played a big part in that, getting the head design so right.
I've read endless inter Company memos where tiny performance enhancing details are worked out. All interesting stuff and quite well executed in general.

After all of that they stuck a potato up each exhaust and dropped it back down to 25 HP all over again!!


Glen
 
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Fast Eddie said:
I get your point. But it wasn’t bean counters that wanted to fit e start or black caps!

The customers wanted e start.

I don’t think anyone actually wanted black caps !
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The Californian market was/is a big one and California insisted that motorcycles produced hushed tones in the early 70s.
Now Ca. has thousands of Harleys running everwhere on open exhausts and even open headers, all apparently legal.
Go figure. $$$$
 
There is one aspect that I can think of where it’s fair to say the mk3 was ‘de tuned’ but whether or not it was international is a another matter entirely… the 32mm port head was shown by Comnoz to be a backward step on a standard engine as the engine doesn’t need the greater flow, but is hindered by the reduced velocity. But how much real world impact this has, I don’t know.
 
Fast Eddie said:
the 32mm port head was shown by Comnoz to be a backward step on a standard engine as the engine doesn’t need the greater flow, but is hindered by the reduced velocity. But how much real world impact this has, I don’t know.
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RH4 vs RH10 cylinder head performance

I have read many posts regarding these two cylinder heads. I have not found any hard numbers regarding HP and torque. It would be especially interesting if HP and torque values v RPM were available. Any info or references will be appreciated. Thanks, Ed
www.accessnorton.com www.accessnorton.com
 
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