certified quarter-mile time.

I think you might be chasing an elusive dream here Murray, the existence of a factory built bullet proof 1973 Combat.

There are those in the Vincent club who believe there exists a bike called the Black Widow, a bike so fast it was banned from importation into the US.


It makes good campfire talk anyway :D

Then again, when a stock Black Lightning could manage 186 mph back in 1955, who needs a Black Widow.
 
worntorn said:
Then again, when a stock Black Lightning could manage 186 mph back in 1955, who needs a Black Widow.
Click to expand...

That phrase rolls glibly off the tongue - if you say it fast enough.

Bit like a stock'* MotoGuzzi V8 could lap MIRA at 187 mph back then.

* Full fairing, full race motor.
Only 500cc, note....

Cheers !
 
worntorn said:
I think you might be chasing an elusive dream here Murray, the existence of a factory built bullet proof 1973 Combat.
Click to expand...
It was Roy Bacon that wrote about the factory correcting the Combat engines still in inventory and he stated that compression had not been reduced.

It was the Norton Owners Club that stated there was a 1973 model Interstate with the Combat engine and I am not a member of that or any other club.

Perhaps there is confusion about when the 1973 model year started. For most vehicle manufacturers that would be in the fall of '72. It is almost certain that some '73 model Nortons were produced in late 1972.

The only way there would be an "elusive dream" to chase is if Norton had not sold the corrected Combat engines which means there must be hundreds of them still in storage somewhere. Why don't you go over to Wolverhampton and see if you can find them because new Combat engines are worth a lot today?
 
Murray,Ill leave the search up to you, I have a hunch it would be a fruitless one, although the trip to Wolverhampton would be nice at the right time of year.
On Combat prices, I still see them go cheap now and then. There are buyers who know about the original faults and don't want the possible problems. The fact that most have been corrected can make these bikes a good buy. The only thing is, my take from the Combat owners on this site (Combat Fixes thread) is that a lot of owners have detuned their bikes for reliability , so it defeats the point of having a Combat, although any well sorted Commando is still a nice ride.

Good thread you started, up to 17 pages and still running!

Glen
 
Murray B said:
The only way there would be an "elusive dream" to chase is if Norton had not sold the corrected Combat engines which means there must be hundreds of them still in storage somewhere. Why don't you go over to Wolverhampton and see if you can find them because new Combat engines are worth a lot today?
Click to expand...

Why would Nortons be manufacturing new non-Combat spec 750's for 1973 if they still had large stocks of 1972 Combat 750's that only needed reworking to be saleable in 1972 ???
That makes no sense at all.....
 
Logic & sense are seperate . Issue on ' hold ' , Production components Sheduled .( includeing updates ) . Obsolete stock ( Combat ) upgraded, as time permits .ENGLAND , of ALL places . " MAKES SENSE " :lol: :lol: :shock:
 
batrider said:
I wouldn't quote Roy Bacon on anything. He is usually wrong wrong wrong on his "facts".
Click to expand...
That may well be but it was the Norton Owners Club that printed a picture of a 1973 Combat Interstate. Roy Bacon just confirms where the engines came from.

His books are more right right right than unattributed sources. Do you have better information?

worntorn said:
Murray,Ill leave the search up to you...
Click to expand...
There is nothing for me to search for. Norton ccorrected the Combat engines intalled them in bikes and shipped them out to dealers. There are no Combat engines missing so there is nothing for me to search for.

Matt Spencer said:
..." MAKES SENSE " :lol: :lol: :shock:
Click to expand...
There were bikes with Combat engines sold in 1972 for sure and it is not surprising that a few engines made it into 1973 model year bikes. Besides a year stamped into an identity plate what determines the "year" of the bike? It does not have to be the year it was manufactured.
 
Murray B said:
There were bikes with Combat engines sold in 1972 for sure and it is not surprising that a few engines made it into 1973 model year bikes. .
Click to expand...

Its hardly surprising or a secret that there were Combats sold in 1972 - the Combat was introduced in January 1972, and was gone before the end of 1972.

Be interesting to hear solid details about any Combats in 1973. ?
 
It may well be quibbling, but since the Combat was only made for 1972 then any 1/4 mile comparisons for bikes sold each year are only going to quote the Combats performance for 1972 ?

If you couldn't buy one for 1971, or 1973, is it fair to include its performance in comparisons for those years ??
 
WHO says you couldnt ?? Quibling all right , Hang Them From The Yardarm ,

Originally ' Combat was a ' option ' . Theres a awful lot of timed breather ' Combat's advertised .
1972 is tin plate on Mag bolts , No timed Breather , you see a few of them .
1973 is solid caseing over mag Posn . Few Combat in these advertised .

Talking ' what Ive seen ' advertised . In the Last Twelve Months .

FAIR ? Keel Haul the the Whingers . They were all built in the Same Centurie .
" Fair " ,
We hear you hung another Admiral the other day .
Yes.
But we hear you hung the wrong one again.
Yes.
But Why.
We find it keeps the others on their toes .

:lol: :lol: Crikey . Standards are slipping .We wonder Why.
 
Matt Spencer said:
...SO , how many Combats WERE produced . ?...
Click to expand...
It would be good to know how many Combat engines were produced and when they were fitted to bikes. It would also be good to know when Norton switched over to making the 1973 models.

Regardles of what these dates are there is still some things very wrong with that 1973 Cycle magazine article. They wrote, "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."

What does this mean? Wasn't the SS cam the one normally fitted to the Combat engine? Do they mean it was an S cam or was there a different cam fitted to Combats that has been forgotten?

They also claim the test bike had 10:1 compression but only managed 12.896 seconds for the quarter when their 1970 test of a standard Commando gave 12.69 seconds. If the bike really had a Combat engine it should have been able to run the quarter at least as quick as the standard model.

The article does not seem useful as a comparison of superbikes at least as far as the Commando is concerned.
 
The slower time may be the result of the crude Combat porting job that Dave Comeau discussed in his treatise on Norton heavy twin heads, also some reference to that in the thread on flow testing by Connoz in the Commando section.

It is quite an interesting thread, shows the graphs for all sort of different Norton heads, both standard and with various porting jobs.
Seems the long stroke Commando engine does not rev high enough to make use of a 32 mm port, especially one that is poorly shaped. The engine will make more power with a bit smaller port and correct shaping.

This was also explained to me by Herb Becker , builder of Commando engines that have won at Daytona .

Of the Combat heads, Dave Comeau states that by today's standards of porting , the heads are essentially "ruined"


Glen
 
Murray B said:
Matt Spencer said:
...SO , how many Combats WERE produced . ?...
Click to expand...
It would be good to know how many Combat engines were produced and when they were fitted to bikes. It would also be good to know when Norton switched over to making the 1973 models.
Click to expand...

The Combat specification engine had apparently been available as a "special order" item since 1970-however it is doubtful that many (if any) were fitted to standard road model Commandos.

The first standard production Commando built to Combat specification was supposed to have been 200976 (however lower 200xxx serial number Commandos with Combat spec. engines appear to exist).

According to factory service release N3/32 (Sept. 1972), all Commandos built from serial number 211110 reverted to "standard" specification, but still retained the 32mm carbs with either a "High" (RH6) or "Low" (RH5) compression cylinder head fitted in place of the Combat (RH3) head. It must also be taken into account that not all Commandos built during the 200976-211110 period had Combat engines.

Official 1973 (750 MkV) production supposedly commenced at serial 220000 from March 1973, however 22xxxx serial number Commandos with late '72 build date stamps are known to exist. Certain sources list 212278 as the start of 1973 production.
 
worntorn said:
The slower time may be the result of the crude Combat porting job...
Click to expand...
Since Norton had supplied the test bike it seems reasonable that they would choose a good head for the test machine. The performance in the magazine test would certainly influence sales.

L.A.B. said:
The first standard production Commando built to Combat specification was supposed to have been 200976 (however lower 200xxx serial number Commandos with Combat spec. engines appear to exist)...According to factory service release N3/32 (Sept. 1972), all Commandos built from serial number 211110 reverted to "standard" specification, but still retained the 32mm carbs with either a "High" (RH6) or "Low" (RH5) compression cylinder head fitted in place of the Combat (RH3) head. It must also be taken into account that not all Commandos built during the 200976-211110 period had Combat engines...Official 1973 (750 MkV) production supposedly commenced at serial 220000 from March 1973, however 22xxxx serial number Commandos with late '72 build date stamps are known to exist. Certain sources list 212278 as the start of 1973 production.
Click to expand...
Written sources often have errors or omissions. In some instances, as in the case of government war records, they can even contain encrypted or false information. After extracting the informatin then there is the problem of interpreting the data. It is sometimes difficult to get the facts.

Model year and production year may be different. For example - 2012 Camaro production began in July 2011 so I expect a great many 2012 models were actually made in 2011. See http://www.camaro5.com/2012-camaro-production-begins

There is no reason that a 1973 model Combat Interstate could not be produced during 1972. This all depends on when the factory started making the '73 models. It is entirely possible that no Combat engines were fitted to bikes during 1973 and yet there were bona fide 1973 models with factory Combat engines.

None of this explains why the 1973 test Commando ran two tenths slower than the bike tested in 1970. There is something very wrong with that later test.
 
Its only 2tenths.

Reaction time, tuning, weight of rider, wind velocity, and the efficiency of the rider are some of the variables.
1/4 mile times vary a lot with the same rider on the same machine on the same day at the same track.

Change any of the above and variations increase.



For example, dragtimes list Honda rc51 times from 10.7 seconds to 12.4 seconds with a number around 11.1 to 11.7.

That is a 1.7 second variation for a cookie cutter Honda, built with Modern methods and near perfect quality control.

Glen
 
Murray B said:
In the Norton Owners Club's "Commando Service Notes" they even provide a photo of one with the caption, "One of the most popular, the 750 Interstate 1973, with Combat engine, signified by black barrels. Photo credit: Motor Cycle"

Notes posted at
http://archives.jampot.dk/Book/Workshop ... _Notes.pdf

So there is little doubt that at least some Combats were sold in 1973 and there is no reliable source that shows they had their compression reduced or their hot camshafts removed.
Click to expand...

The caption reads: 1972 in my actual copy of the NOC Service Notes! (That online copy contains lots of typo's)

That Interstate with the registration number "KJW 375K" was a much photographed 1972 press bike and it certainly appeared in a number of motorcycle publications including the September 1972 issue of Motorcycle Mechanics-therefore it must have been tested at least some weeks prior to that magazine issue date (and the September issue would probably have been available by mid-August).


Also, if you had an understanding of the UK vehicle registration system-you would have known that a "K" (KJW 375K) vehicle registration would only have been issued between August 1971 and July 1972.


Edit:
http://www.andover-norton.co.uk/NBCommandoPortf.htm

test of the first Interstate with the infamous Combat engine, KJW375K, which very machine I sold to a German customer in 1980 due to lack of money to hang on to it- and still mourn the fact.
Click to expand...
 

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