Norton Commando History
Article by Mark Trotta
From 1968 until the demise of the original company in 1977, the Commando was the main bike in Norton's lineup. Powered by a 750cc parallel-twin, later enlarged to 828cc, the Norton Commando was offered in various models. Hallmarks of this classic British motorcycle were performance, mechanical simplicity, and a unique engine mounting system.
Throughout the forties and fifties, British bikes dominated motorcycle performance and racing venues. However, by the late sixties, Japanese manufacturers started producing faster, cheaper, and more reliable motorcycles, severely cutting into the sales of both British and American-made bikes.
Before the Commando engine, there was the Norton Atlas parallel-twin engine. It was powerful enough, but suffered from vibration at higher speeds. Previous attempts at rubber-mounting the engine helped marginally. The company had neither the time nor the finances to develop a new engine.
Norton's Chief Engineer Bernard Hooper, Dr. Stefan Bauer, and assistant Bob Trigg, devised a system where the engine, gearbox and swing-arm assembly were bolted together and isolated from the frame by special rubber mountings. Instead of the engine being rigidly bolted to the frame, it is hung off the main frame, via two cross-frame tubes, one at the front of the engine and one at the rear of the sub-frame. The suspension system kept the swing-arm true in relation to the engine position, while isolating the rest of the chassis from the vibrations of the engine.
Norton took their 750cc Atlas engine (actually 745cc) and developed a new frame, tipping the engine slightly forward. Bolts holding the powertrain assembly to the main frame passed through rubber buffers in the tubes, isolating the engine from the frame. This allows the engine to "float" on the vertical plane, with lateral movement controlled by shims in the mounts. This eliminated the extreme vibration problems, effectively separating the rider from the engine.
The Isolastics anti-vibration system did reduce vibration, as long as the required free play in the engine mountings was at the correct level. Too little play brought the vibration back and could crack the frame, and too much play brought handling issues, particularly fishtailing in high-speed turns.
750 Norton Commando
Soon after the 750cc Commando Mark-1 Fastback was introduced in 1968, a second model arrived. The 750-S sported a high-mount left-side exhaust and a smaller 2.5 gallon gas tank.
The first Norton Commandos had an engine prefix of 20M3. Ignition points were in the magneto and there was an external rev-counter drive. In 1970, ignition points were moved to the timing cover, and the rev-counter drive was now integral. Engine prefixes became 20M3S.
Commando Roadster and Fastback
A new updated S model, called the Roadster, featured conventional low exhaust pipes with upward-angled mufflers. September of 1970 saw the introduction of the Commando Fastback Mark-2, with a modified stand, chain guard and alloy hand levers.
Commando Street Scrambler/Fastback Long Range
The Commando Street Scrambler and the Hi-Rider appeared in 1971, along with the Fastback Long Range, which featured a larger gas tank. The twin leading-shoe brake drum up front was replaced by a hydraulic disc brake.
Nearly parodying bicycles such as the Schwinn Sting-Ray and Raleigh Chopper, themselves parodies of Harley choppers, Norton rolled out the Hi-Rider in 1971. A variant of the 750 Commando, the Hi-Rider featured a high handlebars and a "banana" seat with backrest and short sissy-bar at the rear.
Other features on the Commando Hi-Rider included a small headlight and small 9-litre (about 2.4 gallons) gas tank. Although it stayed in the line for several years, few Hi-Riders were sold. Curiously, it outlasted the high-pipe S-model.
Norton Combat Engine
In 1972, the Combat engine was introduced with the appearance of the Mark-4 Fastback, along with an updated Roadster and the 750 Interstate. The motor delivered 65-horsepower at 6,500 rpm with a 10:1 compression ratio. The first Combat engines were fitted with 32mm carbs.
750 Commando Mark V
The last of the 750 series, the Mark-V was produced from November 1972 to mid-1973 as a 1973 model. Engine bearings were improved, and compression reduced to 9.4:1, both helping engine reliability. 1973 also saw the Long Range model discontinued.
850 Commando Mark 11
Starting in January of 1973, the Mark 5 Fastback was launched and the Long Range was discontinued. Commando engines saw an increase of bore and stroke, now 77mm x 89mm, displacing 828cc (advertised as 850cc). The Roadster, Hi Rider and Interstate were all fitted with the larger engine.
Compression was further reduced to 8.5:1 with the engine now producing 60-horsepower at 5,900 rpm. Increased torque from the longer stroke seemed to make up for the reduced horsepower. The earlier 750cc cylinder head, well designed and factory-ported, was retained.
In 1974, the Commando lineup included the Roadster, Mark 2 Hi Rider, and Mark 2a Interstate.
John Player Norton Commando
Introduced in late 1973 and reaching the public in 1974, the John Player Norton (JPN) Commando was available with either the 750cc engine or the 828cc engine. Approximately 200 John Player Norton replicas were produced and all had right-side shifters.
850 Commando Mark 111
Due to popular request, electric start was introduced on the 850 Mark III Commando. Fortunately the kick-start was retained, as the electric starter was not totally reliable. A front disc brake also appeared around this time.
For the Mark III, the Isolastics system was upgraded. A paired-spring rated to carry the weight of the engine and transmission assembly was designed, taking the load off the Isolastics mounts.
Right-Side to Left-Side Shift
In 1975, new federal regulations required all motorcycles sold in America to have left-side shift and right-side brake controls. The Commando's competitors bikes also switched from right to left, including the Triumph Bonneville and the Harley-Davidson Sportster.
The Commando models, now weighing 460 pounds, were reduced to two models, the Mark III Interstate and the Roadster. A rear disc brake replaced the previous rear drum, and the air cleaner and mufflers were changed to meet U.S. requirements. These two models remained unchanged for 1976.
Last Year Norton Commando
1976 was the last year of the Norton Commando. Norton motorcycle production ended in 1977. It is estimated about 1,200 bikes were built in 1976 and 1977. Although 30 units were sold in 1978, they were actually leftovers built in 1977.
Norton Commando Performance
In the March 1970 issue of Cycle magazine, tests were made on all then-current super bikes. Of the seven bikes tested, a Norton Commando-SS ran the quarter-mile fastest, at 12.69 seconds. The Honda CB750 stopped more quickly, but the Norton was faster.
Norton Commando Problems
The Isolastics anti-vibration system, while reducing vibration, needed regular maintenance. On the last Mark 111 Commandos, adjustment was easier, and a conversion to the later Isolastics is available for earlier models.
Although the Norton parallel-twin engine was reliable and well-engineered, the bike's electrics were suspect and accounted for a fair amount of breakdowns. It was not uncommon for electric-only Commando owners to resort to push-starting their machines.
Main Bearing Problems
Main bearing failures and broken pistons were often encountered with early Combat engines. However, after upgrading main bearings and installing a modified breather, they reportedly were more reliable.
Many British motorcycles, including Norton, continued using Whitworth-sized nuts and bolts into the late sixties. To make things confusing, some seventies models had a combination of sizings! For example, a 1975 Commando Mark 111 has a combination of metric, SAE, and Whitworth nuts and bolts. To compound this problem, previous owners may have changed (or damaged) the original hardware while removing them.
If you don't own them already, consider investing in a set of Whitworth tools for your classic British motorcycle.
Norton Commando Value
An original Norton Commando is one of the most prized bikes in today's classic motorcycle market. It has both excellent performance and good parts availability. Over the years, it has remained one of the most desirable classic British bikes. Many will argue it was the best.
Commando owners in general don't seem to be obsessed with originality as are some other marque's. Examples with sensible modifications often sell as much as 100% original machines.
Norvil Motorcycle Company
Over the last several decades, many component updates and improvements have been offered for the Norton Commando. One of these is the Norvil Motorcycle Company. British-owned and family-run, they have manufactured genuine Norton spares and will ship anywhere in the world. They also produced complete motorcycles, which they did not offer worldwide shopping. The company has been in business since 1980 and has acquired some Norton trademarks, including the hybrid name 'Norvil'.
Norton Vintage Rebuilds
Based in Portland, Oregon, Kenny Dreer's Vintage Rebuilds started restoring and upgrading Norton Commandos in 1995. Since then, the company has started producing complete motorcycles. In the early 2000s, production of the all-new Commando 961-SS began.
Colorado Norton Works
In 1997, Colorado Norton Works began taking old Commandos and addressing their shortcomings. They began developing parts and making modifications to improve the original bike. These upgrades include the engine, brakes, and suspension.
Norton Motorcycles LTD
Norton Motorcycles (UK) Ltd, established a new factory at Donington Park, Leicestershire in 2008 to manufacture a new Commando model, designed by Simon Skinner. In March 2010, Norton produced the first new Norton Commando, model 961-SE.