by Shawn Downey
The blazing sun seared my pigmentless skin, but my attention was diverted from my aching epidermis to the screaming neon motorcycles rapidly approaching turn five. The exhaust notes from this chorus of unrestricted pipes would make an EPA agent squirm like a slug on hot concrete. But to me, the blatant tunes were a panacea to the scorching sun that will surly give me gator wrinkles or a skin melanoma. When guys like me get too close to a light bulb–ZAP–immediate sunburn.
Sunburned and dehydrated I rode down to Milwaukee sans ear plugs to experience the full effect of my “competition only” exhaust at highway speeds. Redline shifts, a friend’s recently installed Supertrapps and an unrestrained Moto Guzzi created an audio euphoria that made meforget about the thirst and burn. I basked in the aftermath of the ride and enjoyed several caffeinated coffee drinks at Milwaukee’s motorcycle friendly coffee house. I was contemplating the origin of the magical motorcycle exhaust tone when I heard the reverb of a Norton Dunstall.
Paul Dunstall was the grand-daddy of the highly coveted tuned exhaust tone. Any amoeba with three fingers and a dull hacksaw can whack the cans off an exhaust system and produce the ever-popular straight pipe blast. Through years of experimentation, Paul Dunstall came to understand “back pressure” and how it related to high compression pistons and horsepower. His first foray into the high performance market was his swept-back pipes designed not only for horsepower but also to allow the fitting of a narrow fairing to his race-prepped Norton Dominator in 1959. By 1960, his Dunstall exhaust systems were the rage, paving the way for his future add-on race accessories like clip-on handlebars, headlight brackets, rear sets, and fiber glass gas tanks.
During his constant pursuit of the perfect tune, he experimented with a variety of cam profiles, carburetor bell houses, and exhaust chamber shapes. He felt that the exhaust flow was the secret to obtaining the ideal horsepower and securing the hottest hotties. Well, maybe not the latter. As he expanded into other high performance mods such as the note worthy seats, tanks, and fairings, he never lost sight of the all important exhaust chambers. He felt that the chambers were the nucleus of the high performance mods and designed around them. By 1967 Paul Dunstall was building and selling so many modified Nortons that his country of origin considered him to be a “motorcycle manufacturer” and taxed him accordingly. This tax status allowed the owners of Dunstall Nortons to run against riders of other standard production machines in the Standard Production racing class and qualified him for homologated racing rules. Hmmm, should I buy a Dunstall Norton that looks, sounds, feels, and tastes like an all out GP race bike or should I buy a stock street bike?
As is typical with all historical losers, the riders of lesser bikes banded together and cried, “Unfair advantage.” Unlike present day governing bodies, the Auto-Cycle Union cried back, “Who cares?” Rapid success fueled his creativity and soon he was developing Triumphs with redesigned camshafts, one inch over monoblocs, polished ports, lightened rockers and cam followers, bronze valve guides, high compression pistons, and guess what? A Dunstall exhaust system.
Norton International consulted Paul in great depth upon release of the Norton Commando and even distributed his brochures detailing three separate after-market kits boasting top speeds of 120 mph to 137 mph. Too bad none were ever produced. Paul was very aware of the direction in which Norton was heading. Maybe he should have told the Norton guys. He began development on a variety of exhaust systems tailored towards the Japanese marquees and was quite taken with the two-stroke Suzuki GT550. Emphasizing power over noise, the UJM’s were more than willing to listen to Paul’s mantra and assisted him in developing Suzuki GS750s capable of 150 mph by 1979. Paul’s last well-known production machine was the 1981 GS 1000 R complete with high lift cams, oversize valves, a close ratio gear box and an endorphin producing exhaust scream.
So the next time you are pulled over on the shoulder of the road and Officer Friendly begins interrogating you on exactly what could have possessed you to surpass the speed limit for the past four miles (No, it did not just happen to me. Okay, maybe it did.), do what I do. Turn the key, crank it up to redline and let it burble. One of two things is going to happen: the Officer is going to mirror that crazed look in your eyes and match your silly grin, or the officer is going to insist you experience the hospitality of his local taxpayers. If the latter happens, be sure to bring along that digitally mixed CD you produced when you dragged your computer out to the garage to record your newly installed after market exhaust system and revel in the audio…