FORGOTTEN MOTOCROSS TECH: ALUMINUM TWO-STROKE PIPES

Motocross history is filled with creative ideas that were heralded as ground-breaking, some were abandoned, others stupid and a few were truly innovative. Do you remember aluminum two-stroke exhaust pipes.

Back in 1974, a pipe builder in Dallas, Texas, named George Banke was building Husqvarna up-pipes out of aluminum. It was a radical idea for the time, but the concept never caught on; it just lay dormant for 25 years. Then, suddenly, two decades later, two companies roared back into the aluminum pipe business, and, just as fast, they were out of it. In 1999, Pro Circuit Racing and Power Brand both decided that the market was ripe for something new in two-stroke exhaust systems; but, the public wasn’t buying the idea of an aluminum exhaust pipe.


In fact, there is nothing drastically wrong with the concept of an aluminum exhaust pipe. Here are the facts about aluminum two-stroke exhaust pipes: (1) An aluminum pipe can weigh as much as 3 pounds less than a comparable steel pipe. (2) Overall power can be identical with the right specs. (3) Aluminum pipes can’t rust. (4) Structurally, an aluminum pipe can be as strong as a steel pipe (by using 0.090-inchwall thicknesses compared to 0.035 inches in steel). (5) The exhaust gas temperature of a four-stroke makes the use of aluminum impossible, but two-strokes do not come close to aluminum’s 1200-degree melting point. (6) Unfortunately, in 1999 dollars, the aluminum two-stroke pipes cost $320 while steel systems cost $170. Why? Material costs are higher and the labor is more intensive.Today, there are no aluminum pipes being made (and there weren’t any made after 1999). The public didn’t want to pay the extra premium for the weight savings (and never truly believed that an aluminum pipe was as strong as a steel one).

 

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