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1971 Norton Commando Custom – Factory Parts Only!

The challenge was to customize the 1971 Norton Commando using only factory parts.

Over its eight-year production run the Norton Commando wore many different guises. All used what were essentially the same chassis, drivetrain, suspension and wheels (with the later addition of disc brakes and electric start). Apart from that, the differences were in the bodywork, gas tank, exhaust system and seat. These were easily removable and replaceable. That meant Commandos were perfect for customizing. But could you create a unique, cohesive custom Commando with only factory original parts? That’s what  Jim Bush wanted to find out, and his Interback project started with a 1971 Norton Commando Roadster. 

Bush first found the bike as a rolling basket case in 1994 and bought it with the intention of restoring. It was advertised as “original, needs work,” but when Bush went to see it, he quickly realized it had been on the way to becoming a chopper before the owner lost interest. It had a beer keg gas tank, a tombstone tail light and the chainguard had been cut to allow a wider 16-inch rear wheel. It had been “stored” for 12 years, and “the jugs have been punched,” he was told. On the plus side, the frame, engine and gearbox were all matching numbers.

Bush got as far as getting the engine running, then consigned the bike to the back of his shop for later consideration. It languished there for a number of years while other projects took priority before he sold it to Tony Duffett in 2005. Duffett completely dismantled the Norton Commando and fitted the engine with a gas-flowed cylinder head from Jim Comstock (www.nortonmachineshop.com), high-compression pistons and 4S-grind camshaft, together with re-sleeved carburetors and Boyer ignition. The stock timed breather system was augmented with a non-return PCV valve to reduce oil leaks.

Bodywork was stock Roadster with a Corbin seat, and with purple metalflake paint on the gas tank and side panels—applied by Bush. Duffett’s Roadster was a show winner, taking first in class at the Tsawwassen Classic & Vintage Show ‘n’ Shine in 2013. Sadly, Duffett passed away in December that year.

“He called me in October from the hospice and asked me to find a home for his bikes,” says Bush. “I immediately said I would make a home for the ‘71 and then found a home for the “R” amongst his friends. 

“The purple metalflake takes some getting used to, and always had been identified as Tony’s bike, something I needed to respect; yet I wanted a daily rider that would still honor his meticulous work.”

As a good friend, Bush knew the bike would always be “Tony’s” while it was still in its Roadster finish. So he decided to donate the gas tank to Duffett’s widow Laura as a memento, and donated one of the side panels to a group of Duffett’s riding friends.

“The other side cover is on a stand in my shop as a reminder,” says Bush.

So Bush now owned a fully restored 1971 Norton Commando without bodywork. Rather than build yet another stock Commando, Bush decided to set himself a challenge: could he create a satisfactory custom Commando using only factory parts? The “Interback” was the result.

The gas tank is a fibreglass Interstate tank (Interstate tanks came in two sizes in steel as well as in fibreglass until that material was banned in the US around 1973.) 

The seat originated on a Fastback LR, though Bush has shortened it by about an inch to accommodate the larger Interstate tank. The tailpiece is from a regular Fastback, and side covers from a Roadster. Complementing the café look is a pair of headers from an SS model, fitted with mufflers intended for a 1972 Interstate. The finishing touch is a set of rearset footpegs from Norvil (norvilmotorcycle.co.uk).

Norton commando factory custom riding shot

The result is a spectacular custom machine that looks like it had come from the pen of a top Italian designer. The unusual combination of components looks just right—and works beautifully. And the six-gallon gas tank gives a range of over 300 miles.

Most recently, Bush has also updated the Interback to provide a better “user interface,” with an electric starter kit from Alton (www.alton-france.com). The Alton kit includes a new inner primary case that carries the starter.

“The Alton starter is installed and works like a dream,” says Bush. “A two-hour install.”

Also fitted is a Power Arc ignition system with switchable ignition curves from Old Britts (oldbritts.com).

“I wanted to make sure the voltage drop issues with the older generation Boyer was avoided to eliminate possibility of kickbacks,” says Bush. “This has woken up the motor somewhat as well. It runs absolutely perfectly, idles so smooth.”

For the future, a Norton-Lockheed disc front brake is in the plans, combined with a sleeved-down master cylinder using a kit from RGM for extra stopping power (rgmnorton.co.uk). Front forks will benefit from a Lansdowne cartridge valve conversion (lansdowneengineering.co.uk). 

Norton commando close up on gauges and bars

“I love the comfort of the wide LR Fastback seat,” says Bush. “The rear sets put the feet in the right position, and an inch and a quarter chopped off each side of the stock Interstate handlebars makes it feel very comfortable on the arms. 

“The high pipes and Interstate mufflers sound rich with a nice bark! My plan was to build a modernized 1971 Norton Commando, staying away from all the usual café bolt-on bits that abound on the internet sites. With the disc brake, upgraded suspension, electric starter, comfortable seat, large capacity gas tank, tool storage in the tail piece, it will retain its classic character and good looks—and be a bike that is ridden.”

Norton commando custom interbackclose up on two tone tank

by Robert Smith Canadian Biker Issue #329

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