71 0r 72 ???

Hi All. New commando owner and restorer here.
May I pose a question to those more knowlegable than myself.
I have just purchased a commando, the plate says made in Dec. 71. However it has a combat engine and front disc brake, which I believe didn't arrive till 72.
The question is , for the purpose of parts sourcing IDing etc., should I consider it a 71 or a 72 ? The engine and frame No. is 202***.
Also did they come out with fibreglass tanks and sidecovers ? There sure is a lot to learn ....
Thanks in advance.
Great site with ton of knowlegable folk. Glad to be a part of it.

If the disk and head are original then it's a Combat. Like most vehicles they are built before the model year, so a late 71 build is a 72 model.

Combat Col said:

the plate says made in Dec. 71. However it has a combat engine and front disc brake, which I believe didn't arrive till 72.

should I consider it a 71 or a 72 ? The engine and frame No. is 202***.

Click to expand...

Even though it was actually made in late '71, you can consider it to be a 1972 (200000+) model .

Combat Col said:

Also did they come out with fibreglass tanks and sidecovers ?

Click to expand...

Fibreglass tanks were used from the start of production in '68 and lasted until 1973.

I've had two '72 750 combats. First showed Sep '71 and VIN 201123. The current is Dec '71 and 2018xx.

My '69 'S' has an ID tag on it that says APR 1969. But it was registered for sale the first time in 1970 and the title shows that. So, I consider it a '69 registered in '70. I guess if it never got sold until 72, it would have been a 72. Just need to define your terms.

Dave
69S

A low rear crankcase breather hose and smaller fin gap at head seam do milled head for 10 CR is unique to Combats with hi rev wet sump tendency d/t eager urge to rev hi. 2S camshaft, but would take valve lift graphing or run up past 6800 to tell.
Combats are the cream of the crop to me.

hobot said:

A low rear crankcase breather hose and smaller fin gap at head seam do milled head for 10 CR is unique to Combats with hi rev wet sump tendency

Click to expand...

All '72 and '73 750 models are supposed to have had the rear crankcase breather, and not all '72 models were built to Combat spec, and no '73 models were apparently, so the presence of the rear crankcase breather does not identify an engine as being a Combat.

It's probably been answered, and I probably read the answer, but:

As anyone can port, mill, and stamp a head with a "C",

and

as anyone can install a 2S camshaft,

and

as anyone can install the appropriate pistons,

-is there a definitive schedule listing specific serial numbers of factory-produced Combat engines?

My guess is that there are probably a fair number of illigitimate copies out there...

I figure if it looks like a Combat, smells like a Combat, and has all the components of a Combat, then it doesn't really matter much if it came from the factory that way unless you are looking for a concourse bike.

Speaking of installing a 2s cam, what kind of problem is it to measure a cam using a degree wheel and valve lift to verify the cam?

L.A.B. said:

hobot said:

A low rear crankcase breather hose and smaller fin gap at head seam do milled head for 10 CR is unique to Combats with hi rev wet sump tendency

Click to expand...

All '72 and '73 750 models are supposed to have had the rear crankcase breather, and not all '72 models were built to Combat spec, and no '73 models were apparently, so the presence of the rear crankcase breather does not identify an engine as being a Combat.

Click to expand...

Build date on my steering head tag says October 1972 but it is a 1973 model; it is a Combat - 32s w/ 32 manifolds and ports, "C" head, breather on rear of engine, black cylinder, close gap between fins of head/cylinder, wants to over rev, square '73 tailight, basket weave seat, AND serial # stated on engine and trans is # 220000.

low rear crankcase breather hose "AND" smaller fin gap

Click to expand...

In my polite defense I'm not misleading anyone, please note the AND part for 10:1 CR that other 750's do not display visually or in power delivery.
W/o looking I can now tell a real Combat by just holding WOT in 4th, there will be no end to rpm's or torque climb till the engine bombs. Norton could have saved its life by just putting a rev limiter in them Combats. IIRC more Combats made than any other Commando version and I'm so glad of it. A non-Combat in low 200--- s/n's would be the rarity to find.

ludwig said:

rvich said:

.. what kind of problem is it to measure a cam using a degree wheel and valve lift to verify the cam?

Click to expand...

Is this a rethorical question , or do you really want to know ? ..

Click to expand...

It is on my winter list of things to experiment with. I have done some searching here but haven't found it, but probably I have not yet found the correct set of words to use in the search. So, take me to school, direct me to some reading or offer tips. Otherwise I will be trying to figure it out at some point anyway.

It seems like it would be a good skill to have and would be one more tool for a person who was trying to identify if their 750 were a Combat (so almost related to this thread). It seems that it would also be a good thing to record and check back for cam wear.

Russ

xbacksideslider said:

Build date on my steering head tag says October 1972 but it is a 1973 model; it is a Combat - 32s w/ 32 manifolds and ports, "C" head, breather on rear of engine, black cylinder, close gap between fins of head/cylinder

Click to expand...

It has a Combat head, but is there any proof it actually left the factory like that?

The first detuned Combat was supposed to have been serial 211110, but even the detuning on those models amounted to nothing more than a thicker head gasket.

xbacksideslider said:

square '73 tailight, basket weave seat, AND serial # stated on engine and trans is # 220000.

Click to expand...

220000 is an interesting number, according to the "official" records that would make it the first 750 MkV supposedly built in March 1973.

Wrenching is only a small part of being a real mechanic, measuring stuff accurately is more what make ya competent, accomplished mechanic, even if you don't put a thing together. Tedius to a fix a dial gauge over installed head to graph crank degrees and valve stem lift. Easier to have head off and rear on lifter tops.
I've saved DynoDaves text-graphing of Combat and compared to my measures to see indeed I've 2S cam. If you take time to do all 4 lobes, my respects but allows monitoring of wear over time.

Factory 2S cams are stamped "SS".

Of course anyone could also stamp any otherwise unstamped cam twice with an "S" stamp and a hammer...

So, measuring / verifying cam profile could come in handy.

xbacksideslider said:

L.A.B. said:

hobot said:

A low rear crankcase breather hose and smaller fin gap at head seam do milled head for 10 CR is unique to Combats with hi rev wet sump tendency

Click to expand...

All '72 and '73 750 models are supposed to have had the rear crankcase breather, and not all '72 models were built to Combat spec, and no '73 models were apparently, so the presence of the rear crankcase breather does not identify an engine as being a Combat.

Click to expand...

Build date on my steering head tag says October 1972 but it is a 1973 model; it is a Combat - 32s w/ 32 manifolds and ports, "C" head, breather on rear of engine, black cylinder, close gap between fins of head/cylinder, wants to over rev, square '73 tailight, basket weave seat, AND serial # stated on engine and trans is # 220000.

Click to expand...

Wow, 220000 was supposed to be the first '73 750. Is that number real? If it has a "C" head also interesting as in '73 the 750s had RH5 (low compression) and RH6 (high compression) heads. At Norton anything is possible on the specs assembled. Not sure if the high compression models had other than a "standard" camshaft. My '73 750 with build date Nov '72 had VIN 220627. It wasn't as fast as a '72 combat.

More on combats..from the NOC website and also where I get my illf8ed:

1973

The Commando was now settling down after all the warranty claims from the ill fated Combat (discontinued from engine No. 211110)

illf8ed said:

220000 was supposed to be the first '73 750.

Click to expand...

220000 would make it the first known 750 MkV model, which isn't necessarily the same thing.

In the mid-late 70's an old high school friend who regretted that I had sold my 1971 Commando more than I did, called me. He was a "sound man," a recording engineer, in Hollywood; he told me that he knew a guy who was "in the business" with a Norton that might be for sale, and that we ought to just drop in and make an offer.

We went down into Hollywood, near Melrose and Highland, and there it was, under the generous eves in the side yard of a 1920's "craftsman" house. It had 3500 miles on it, a dead battery, and rusted out peashooters. $600 later, I owned this bike - #220000. I believe that I am the second owner. It was dead stock when I got it.

I put another 12000 miles on it before a K&N air filter dropped a piece of stainless steel wire down the right cylinder and gouged a trench. I pulled it apart and handed the head and cylinder to CR Axtell and his partner Mike Libby. Ax did the head and there it sat while I waited for Mike to weld and grind a batch of cams. Mike never got around to it and I wasn't able to move the project along anyway - wife and kid and house. All three of my bikes sat for 15 years. The GSXR1100 just dried up, the cracked block SR500 hot rod just sat there, and the Norton, less top end sat there too.

Three years ago my daughter graduated from high school and went off to college and I told my wife I was gonna resurrect the bikes. We'd courted on the Suzuki; it was easiest and first, then the Norton, the SR still sits there.

Last year I settled up with Mike and picked up what he said is the last Norton head that Mr. Axtell ever touched and it now graces #220000.

Since there seemed to be some skepticism about #220000, some more pics -

Transmission #



Steering head/frame #



Steering head build date




32mm carbs



I hope to build a Heim joint head steady next week end so at that time I'll take some pics of the "C" on the head and look and see if there is a "RH" stamp too