Cycle World Editors dig Commandos.

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Nov `12 C.W., P. 59; Article on 'middle-weight' bikes:
-with an action pic of a Commando at the strip doing a smoky burnout, captioned thus..
"Big, bad, tyre scorching superbike! The Norton Commando of course. & yet, looking back, it is a narrrow, lightweight motorcycle with tractable power & great fuel economy - very 'middle-weight' characteristics."
 
Hehe, if ya let more air out the rear it don't smoke it freaking HOOKS UP!

Cycle World Editors dig Commandos.
 
Do the C.W. editors read this forum?
If so, perhaps they could help solve a Combat mystery.
One of the Commando fettlers who did that Dec `72 Cycle Superbike Showdown, Bob Yacenda, recently had a brief letter published in C.W. referring to the matter.
Could he be contacted for more information, like - was the test Commando a derated Combat, & other questions?
 
@ one up
I agree that max revs on an 850 should be about 6000. I always try to change lower than 7000 RPM, but with the close box and the rebalanced crank, it invariably spins up to 7.500 rpm. Should I take out more life insurance ?
 
This redline limit stuff is tough to get me head around. My 750 P!! was made/marked for 9000 and a few others that race also say theirs was effective=lasting to 9000. We had a thread that showed the 89mm stroke got overwhlemed with friction much over stock red line so is counter productive power wise to rev higher. I was still going off my P!! sound-reflexes on my 1st Combat in '99 [pre-Peel] and almost died passing a semi before on coming and doing fine till about cab level the Combat sounded like was blowing up and power dropped suddenly so had to up shift losing some yds to just squeak by in time. On other engines I've pressed you can sense their drop in pull to know time to shift, but not Combats nor likely the racer engines, they just pull harder right to destructive power loss. I don't know if points or valves floated in my semi learning curve but it ran fine there after and did not watch tach as watching oncoming vs semi closing space to dart into. I do0n't think there's much if any extra wear running up close to redline as oil pressure surf wedging in full flow. Its the crank flexing and binding its end bearings and the rod shells on journals I think limit safe rpm. For those pressing rpm limits I highly recommend a rev limiter in case of missed shift or stuck throttle or drive train let go. Steve Maney w/o JSM light piston and rods, runs his 920's to 7200. There are non-linear relationships that is hard for humans to relate to, ie: 1/4 faster spin = doubling of loads.
 
At one stage I upped the overall gearing to knock the backside in, on my 850. It just went faster, still revved too high, and first gear was then too high for the clutch starts. I wasn't smart enough to fit a standard Commando first gear to the four speed close box, so I sold a good TZ350 Yamaha, and bought the 6 speed TTI gearbox with first gear almost a slow as a standard commando. I am amazed at the torque the 850 delivers, I still haven't reached the gearing limits, and I don't believe I will ever get it right for a big circuit like Phillip Island.
 
There are two main factors of Norton over revving, one the crank flex in our un-center supported cranks and two the piston-rod jerk down-apart force that is more acceleration related than speed itself weakness. Found this blip on JE pistons that Jim has sourced for us.

JE Pistons is the largest manufacturer of forged ... racing pistons in the ... Endurance Limit 125 MPa 18,000 psi SRP pistons that are made from 4032 alloy

If any able-willing to convert MPa measure into piston inertial mass loads then into G force measures, below calculator may give limits to piston rpm in our various rigs.

Racer math
http://2.3liter.com/Calc2.htm#PistSpeed
 
So, perhaps, a roller crank could solve certain described problems -lubrication/plainbearing bind/torsional flex moments - in 1 fell swoop?
 
The other fettler of that Dec `72 Cycle test - [query?] Combat was Brian Slark, who is/was a senior type chap for the Barber Complex, I dont suppose anyone here knows him/is in contact? He could also likely provide some information of interest.
 
I routinely spin my '73 850 to 7k on acceleration through the gears . I realize that the HP peak is significantly lower but the motor seems to rev quite happily and easily to 7. There are no go-fast parts in the motor; in fact there is one go-slow part, the 750 pipes instead of the balanced 850 pipes. ;)

I don't see any reason to baby these bikes; they were "super bikes" once so I expect mine to act like it on occasion! That being said, with the upright position, the bike is most comfortable for me at around 75MPH - virtually no engine vibration and not too much wind. In New York the bike would indicate 120MPH at the top end though in Mexico, at 6-7000 feet, where the bike now operates, 105 is about all I have been able to get out of it. Yes, my wife's 2012 BMW F650GS (800cc) will out run it. But a current Harley won't (not that that is saying much)!
 
Acotrel Ms Peel also liked the higher gearing and often skipped taking off in 1st if already in second and then would often skip 3rd as a time waster to snick to top to feel the long hard pull to top out. JAW about everything has been tried crankshaft wise but for my eliptical-planetary crank so we are stuck with a jump rope rpm limiter there. I've known and called Brian Slark since before Barber's left the run down wharehouse in inner city Birmingham Ala. He helped advise Peel's deal some a decade+ago. Might ping him to see if he can fill in details as may be the most informed man alive on Norton detailed history, including how Harley got rubber mounted rod linked wonders nowadays and Evolution heads designed from Brian Hopper after Norton crashed.

Peel 'Combat' was abnormal in build combo's and felt like low 12 sec or upper 11 sec 1/4 miles to me and those trying to keep up in take offs, passes of cars and top out speeds. My current full factory Combat Trixie is a mid 13 sec drag compared that is only good enough not to lose sight of hot rods out for fast fun in best road racing area around. Past Peel could not be out run in 2nd up to 90mph/7600 then 900's above could but Trixie gets outrun on leaving 1st. For comparison my P!! felt like low 11's w/o the flat drag slick. The 3 smokes didn't stand a chance back in their hey day. Only the 1%'r outlaw HD's could keep up with P!! top end but I couldn't hold on long way above highway speed d/t horrific vibration. If I had that P!! POWer plant I'd never given a thought to a blower to keep up with the moderns to like 150.
 
Thanks Hobot, I`ve P.M.`d Bill , it would be cool to get the straight dope on that test, - Combat - or what?
 
Dec `12 C.W. has an Editor`s write-up of his Commando [`74 850 Roadster], Mark Hoyer reckons:
"Forgetting my emotional attachment to this particular machine, the 750 & 850 Commando are perhaps the most practical, usable-in-the-modern-world classic Britbikes.
They handle well, have great power, a good electrical system & a front disc brake.
Most important, Isolastic rubber engine mounts quell what would otherwise be intolerable vibes from the big parallel twin."
 
Sorry it has taken me so long to respond to your request. I have not touched a motorcycle in 40 years, sense I left Norton, so I had to wait for my brother to retrieve some of my old notebooks held in storage all these years. Unfortunately acid paper, disappearing ink, moisture and boxes that could not be found, will limit my response. I used to keep detailed notes on many of the projects and technical back office discussions.

Trying to follow the various treads seemed to reveal several questions that I will try to respond to in no order. But I will try to focus on the Cycle Dec 1972 Superbike comparison. Let me start by saying that to my recollection, we (NVL) were not all that please with the article’s edited form, but felt OK about the Norton’s overall placing based solely on the graded values, although they could have been better.

I was in England when the 1970 comparison test was done, but there was a deep concern about the “cheating” tone that existed during that get-together. So it was determined that the Norton Roadster for this test was to be exactly what a customer would drive off the dealers showroom for all aspects of the testing. NVL was not known for extravagant expenditures, so we did not pull a brand new 1972/73 bike out of the create to use. This Combat Roadster was our demo bike that we had been using as a loaner to magazines, testing the latest upgrades and engineering changes (EC’s) to support our dealer network.

The Commando generated about 45 to 70 upgrades and EC’s a year so before we gave the bike to Cycle, I had to clean and blueprint the entire bike to what was current from front to back. From the picture in the article you will see the black cylinder barrel, so we know it was the combat engine. I could not find the serial number to verify what was in the crankcase, as that was the only part of the bike I did not dig into. The bike was prepped in October 1972, so everything available at that point in time was in or on the bike. Cycle also just published the 750 specs from the sales brochure, except for the Torque and HP numbers that they used from their dyno test. This bike would not have had a 10:1 compression, as I was not using a cylinder base gasket and always used the copper head gasket. Most likely it was the 1mm copper gasket, so the compression would have been 9:1.. not the 10:1 designed for the 2S cam. A note on the cam and main bearings.. we had 3 cams floating around in 72 and 2 sets of main bearings. A standard ‘Atlas’ 750; Combat 750 soft grind, and the Combat grind both known as the 2S grind. The soft grind was a manufacturing error that caused the cam to wear, we had many of those wielded and reground. So to all questioning the cam.. assume it was a Used, NOT worn, 2S. Cycle did not publish the open/close timing specs for the teardown inspection, nor do I have Axtel’s dyno printouts to compare with the Cycle published graphs. The Axtel dyno output graphs for cam tests that I had, are now just blank pieces of paper. Bottom line.. it was the Combat 2S cam in that test bike, set to factory spec. I found no reference to the main bearings used.

The way the article was laid out also differed from the actual test sequence as I remember it. I seem to recollect that the 1st day was the basic run-in and decibel test day. We had some issues that day before we could turn over the bike. The first was a weak spark issue that caused plug fouling. The sentence about “thrashed on the Norton” came from me feverously trying to track down the fault. I ended up bypassing the Ballast resistor to fix the problem. We also dropped the jetting and played with the needle position because of weather conditions that day. The other issue that day was the Norton failing the decibel levels. The mufflers on the early combats had a baffle that caused a whistling at a high frequency that put us over the limit. Brian Slark fixed that by taking a long screwdriver and punching out the baffle, allowing the Norton to pass the test.

Once we turned the bike over to the Cycle guys, we never touched the bike again, so it ran with the leaner jet and the punched out baffles for all remainder testing. Also, because the decision was to use a spec Roadster it would have had the 19 tooth drive sprocket rather than changing to the Interstate 21T for the drag tests. The other two issues mentioned in the article were the clutch slippage and sputtering at high speed. The clutch I would attribute to putting in the new solid metal clutch plates and the other to Amal carb issues with foaming petrol in the float bowl or the small jet restricting gas flow. I think we would have done better with the drag and dyno tests if we played a little with the settings, pushing us up a slot in the standings… The Norm White drag run was a brand new 73 Combat with factory settings, it produced 12.24 sec 1/4 mile... I hope this helps.
 
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