Combat differences

luckyed said:

I’ll add a little something to the lore and also have a question. I’ve got a 750 roadster, serial #211407, build date August 1972. So, just post Combat. The original black tank, not currently in use has the “D” stripe. The instrument cases are polished alloy. The barrels are painted black which looks to be original. Front disc there from new. 32mm original Amals ( little slide wear, I rebuilt the internals and they run fine) 19,000 miles and I’m the 3rd owner. I’ve had it 10 years. The second owner had it sitting around in a collection for 15 years or so and rarely, if ever, road it. From the data provided by Greg Marsh it appears that it would have been built just ahead of getting the factory installed “Superblend” bearings. And it would have been fitted with either the RH5 or RH6 head with the 32mm intake ports. My question: The head has almost no material below the bottom fin, and the gap between the bottom head fin and the top barrel fin is noticeably less than the other fin spacings. Would that be an indication that it is the higher compression RH6 head? (I’ve never had the head steady off to see if it’s marked)

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It should probably has the 3rd bearing iteration - first one called SuperBlend, but not the final SuperBlend if dealer fixed. They quit calling them Combat, reduced the compression and started calling them high-performance. The RH3 head was skimmed .040" where the RH6 head was skimmed .020". AFAIK, the RH6 750s did not have the 2S cam.

Of course, the head could be skimmed or changed after leaving the factory.

Part of SR N3/23

luckyed said:

I’ve got a 750 roadster, serial #211407, build date August 1972.

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The factory supposedly began fitting the R&M 'Superblends' (6/MRJA30) bearings from 211891 so unless the bearings have been changed then 211407 should have the older roller bearings.

Going off in a different direction a bit I bought a British Racing Green Combat Fastback in 1972 from an old guy who had bought it new a month before but found out that he couldn’t start it so it was pretty much a new bike. I thought at the time he was a bit bonkers buying it but a few months along I found out that he had definitely dodged the bullet. It was a lovely looking bike and I had never thought of buying one until I saw the advert and went along to have a look.

Back then the build quality at the factory was very poor but living in England and thinking that British was best so I made an offer, bought it and made plans to sell my 500 four Honda and rode away home. Loved the torque, the presence that the bike had on the road and it was very comfortable too. The next Saturday I rode with a few friends to do our usual Saturday pub lunch thing when one of them rode past my waving his arms for me to pull over and stop and it was then I noticed the huge cloud of white smoke behind. Couldn’t see anything obviously wrong but had to have the bike put into a van to get home and found straight away a holed piston. Found out later when looking in the carbs that everything inside was loose which resulted in a weak mixture and burned the piston one side. I think the bike was still under 450 miles from new. The Norton dealer pretty much couldn’t care less and back in those innocent days just bought a pair of pistons and swapped them after building the carbs properly. The bike was pretty much fine for a couple of months (apart from leaking oil like a worn out steam train) then in quick succession the exhaust pipe head fittings managed to vibrate themselves loose to the point of falling off coming down the A3 at night in pitch darkness at around about midnight, the main bearings went (it was diagnosed as crank flex by the Norton dealer back then), and the Zener diode went and killed the capacitor. By then I had had enough, had the bike fixed and sold it to the (then) friend.

The build quality from the factory was truly shocking by todays standards and the dealer might as well have had a “F@*k Off” post-it note stuck to his forehead. Aftermarket parts I have seen at classic bike shows look to be a far higher quality then the parts fitted new back then and the real shame was that it was a fantastic bike with real character and I really loved it. As a Combat it was just impossible to own as all bikes were daily users back then. I had several friends that had 850’s over the years and all have been great bikes and pretty reliable. The Combat was an act of madness with the build quality back then as an obvious reaction to the new shiny Japanese 750’s just coming in and back in 1972 it was a stretch too far.

I restore bikes now and I would love an 850 project at some point but I’m sure the memories of 50 years ago would still give me sleepless nights.

L.A.B. said:

The factory supposedly began fitting the R&M 'Superblends' (6/MRJA30) bearings from 211891 so unless the bearings have been changed then 211407 should have the older roller bearings.

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Thanks L.A.B., That’s what I was thinking. I don’t know what the original owner did, but it’s held up so far for almost 20,000 miles. No plans to open up the bottom end that’s for sure.

luckyed said:

Thanks L.A.B., That’s what I was thinking. I don’t know what the original owner did, but it’s held up so far for almost 20,000 miles. No plans to open up the bottom end that’s for sure.

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As I understand it, at least some dealers were changing the bearings. It should have left the factory with the 2nd iteration: https://gregmarsh.com/MC/Norton/SR/N2_06.aspx

Most likely if the dealer changed them, it would have been the 3rd: https://gregmarsh.com/MC/Norton/SR/N2_09.aspx

The final was started in Jan 73 but dealers probably had stocks of the 3rd so even if replaced in 73, it might still be the 3rd. 4th: https://gregmarsh.com/MC/Norton/SR/N2_10.aspx

I have no clue of the failure rates of each iteration, but Norton admitted to failures with the 1st.

Seems like I kinda opened a can of worms with this thread asking about the Combat engined bikes that I'm sure has been discussed and argued about plenty of times in previous posts. No offense to any of the Combat owners, of whom I'd guess there are as many who swear by them as those who swear at them, but, for now anyway I think I'm glad to have the more plain Jane stocker that I have. As other have surmised, I suspect it was Norton's attempt to boost performance to compete with the onslaught of the game changing Honda 750-4cylinder.

quawk said:

Seems like I kinda opened a can of worms with this thread asking about the Combat engined bikes that I'm sure has been discussed and argued about plenty of times in previous posts. No offense to any of the Combat owners, of whom I'd guess there are as many who swear by them as those who swear at them, but, for now anyway I think I'm glad to have the more plain Jane stocker that I have. As other have surmised, I suspect it was Norton's attempt to boost performance to compete with the onslaught of the game changing Honda 750-4cylinder.

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Actually, they are sought after today. Most that ask me to build them a bike want a Combat. It's unfortunate that Norton didn't do enough testing before starting to sell them. They were basically sorted out by the time they discontinued them. They were not particularly high compression, and the cam was not overly radical but when you add all the things together, they went from respected to a to a fixable mess.

The Combats sure suffered their share of failures, some more catastrophic than others, back in the day, probably mostly the way they were flogged. If the rule "Last bloke to the pub buys the beer" would have been "First bloke to the pub buys the beer" , the Combat model may still be in production

quawk said:

Seems like I kinda opened a can of worms with this thread asking about the Combat engined bikes that I'm sure has been discussed and argued about plenty of times in previous posts. No offense to any of the Combat owners, of whom I'd guess there are as many who swear by them as those who swear at them, but, for now anyway I think I'm glad to have the more plain Jane stocker that I have. As other have surmised, I suspect it was Norton's attempt to boost performance to compete with the onslaught of the game changing Honda 750-4cylinder.

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The strange thing is that the standard issue 750 Commando was quicker than the Honda 750 four.
It was likely the Kawasaki H2 Triple that Norton was chasing. That came out in 71. Then in 72 Kawasaki brought out the Z1. 82 reliable horses there vs 65 very unreliable horses with the Combat. No chance of winning that fight.



Glen

worntorn said:

The strange thing is that the standard issue 750 Commando was quicker than the Honda 750 four.
It was likely the Kawasaki H2 Triple that Norton was chasing. That came out in 71. Then in 72 Kawasaki brought out the Z1. 82 reliable horses there vs 65 very unreliable horses with the Combat. No chance of winning that fight.



Glen

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Exactly.

worntorn said:

The strange thing is that the standard issue 750 Commando was quicker than the Honda 750 four.
It was likely the Kawasaki H2 Triple that Norton was chasing. That came out in 71. Then in 72 Kawasaki brought out the Z1. 82 reliable horses there vs 65 very unreliable horses with the Combat. No chance of winning that fight.



Glen

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Around 1980 my roommate at the time had the big Kawasaki and we bantered whose bike was faster, so we hit the street for a race. I broke my gearbox
trying to keep up with him, which put my bike in pieces for 40 years as I didn't have the money to fix it then. Bike is great now, but I learned a lesson......

74 Cafe' said:

Around 1980 my roommate at the time had the big Kawasaki and we bantered whose bike was faster, so we hit the street for a race. I broke my gearbox
trying to keep up with him, which put my bike in pieces for 40 years as I didn't have the money to fix it then. Bike is great now, but I learned a lesson......

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So you bought a TTI gearbox ??

Fast Eddie said:

So you bought a TTI gearbox ??

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I called Brian Slark and got price quotes, including for a Quaife 5-speed. On one of my trips to CA, I went to his shop
and still have a written parts estimate from him as well as his parts books and other brochures...Nicely compliments my
original owners and shop manuals....Funny on the parts prices now compared to then.....Stock fresh gearbox now.

worntorn said:

The strange thing is that the standard issue 750 Commando was quicker than the Honda 750 four.
It was likely the Kawasaki H2 Triple that Norton was chasing. That came out in 71. Then in 72 Kawasaki brought out the Z1. 82 reliable horses there vs 65 very unreliable horses with the Combat. No chance of winning that fight.



Glen

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Someone posted a Cycle World superbike comparison test from the early '70s (pre-Combat, while I was still in Primary school!), and the Commando came out of it pretty well, but was well beaten by the Z1.
Conversely, the Honda 750 Four got a very poor rating, only saved from total humiliation by the inclusion of a Harley Sportster

I read that the Combat was created to satisfy the US Standing Quarter brigade, and CW cried foul on the 12.6s advertised time - Cook Nielsen couldn't get below 13s.
Norton sent Norman White out to California and did a 12.24.

I held on to the original Publication of that Magazine. It is Cycle Magazine from Mar 1970 and the title of the test is " Superbike Seven Shootout".
Cycle magazine was a competitor of Cycle World.

In that Superbike 7 testing, Cook Neilsen did get the regular 8.9 to 1 1970 Commando 750 down to a 12.69 second quarter mile, the fastest of the group. Afterward they took all of the bikes apart as the Harley group was screaming that the Norton must have been hopped up somehow in order to go that fast. The Cycle staff found the Commando to be stock but the Harley had been heavily modified for extra power. I guess it didn't work as the Harley was still one of the slowest.
The Z1 was not in the test as it didn't exist yet. The Kawi triple 2 stroke was present in its first form as a 500. At that it was bloody quick but Norton still got the top spot.
In 71 the triple went to 750 cc and the Norton couldn't quite keep up.
In 72 Norton tried with the Combat but by then Kawi had the Z1 as well.
In the book of original road tests I have here none of the Combats went thru the quarter particularly fast. Even fitted with the 19 tooth sprocket they were about the same thru the quarter as the earlier 750s with 19 tooth, on average.
The fastest times were set by 850s with 20 tooth sprockets. They were marginally quicker than the quick 750s with 19 tooth.
No 850s with 19 tooth were tested in the book of tests that I have.

I think Norman's bike had been tuned up quite a bit past stock. And then Norman is a tiny person, not representative of even the average rider back then.

Glen

My stock 850 came from the factory with a 19 tooth front sprocket and too this day still keep it with the 19 tooth front.
I have never been one to prove anything with my bikes but my 850 Commando/Featherbed is a light weight and shorter compared to a Commando and with the balanced crank, 2S cam and port work, tuned open exhaust, carbs jetted right and that big spark from the Joe Hunt, I have always wondered, but my days of flat out riding in top gear to prove anything is long gone, but when I do get the urge to open it up, I know it gets to the ton and over real quick and does it easy, but these days with cameras, patrol cars/bikes with radar fitted have taken the fun out of our lives.
But it's still nice my Norton can do it anytime since I built my hotrod Norton back all of them years ago (1980/82), it's showing its age but still does it when asked, second and third are my play gears.
I have a lot of fun on my lightweight hotrod Norton even after all these years we been together with nothing to prove at all, it just puts a big smile on my dial every time I take it out, love it.

Ashley

"The Norton was sup-posed to have had a hot “Combat” cam in it, but our readings showed the magic stick to be a slightly worn SS cam instead"
Pulled this off the net. For those that don't know, the SS is the stock cam, the 2S is the Combat. Yes, confusing.
I'm also not sure if the bike tested was a Mk IV-72 (True Combat) or a MkV- 73.

1973 SUPERBIKES pg1

I'm not sure if a 'True' Combat Roadster was ever magazine tested.
I believe there was a test on an Interstate Combat, which I think has 21t counter in stock form.
I may be wrong on all this..

Here's one

worntorn said:

Here's one

View attachment 113353

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How realistic is a fuel consumption figure of 40mpg (American gallons)... this equates to around 48mpg (UK gallon)??

That's a bit less than I get with my Commando when on a long trip. It will do around 55 mpg IMP., if ridden in a reasonably conservative fashion over a long distance.

Glen