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KEVIN CAMERON'S SPORTBIKE PERFORMANCE HANDBOOK

by Al

As a schoolboy back in the '70s I used to buy Cycle magazine every month. I thought it was the best motorcycle magazine in the world, for a lot of reasons.

One of those reasons was Kevin Cameron, and his brilliant technical articles.

His first article was published in Cycle in 1973, about the time I started buying the magazine, and his ability to clearly entertainingly articulate his deep understanding of the physical, chemical and mechanical components of motorcycles would make it the first of many articles.

Cycle magazine folded in the late '80s or early '90s, and Kevin Cameron moved on to Cycle World, becoming their technical editor. He's been there for about twenty years, now.

In 1998 he published the first edition of Sportbike Performance Handbook, and last year he published the second edition. A rattling good read it is, too.

Each chapter starts with the basics of the subject, and moves on to the complexities in clear and easy to understand steps.

As an example, chapter three is called "How Engines Work".

It starts with an explanation of the four stroke cycle, moves on to intake flow, valve overlap and early exhaust valve opening, and discusses ignition and the importance of turbulence in the combustion process.

This leads into types of charge motion, combustion spaces and flame propagation, compression ratios and peak pressure, cooling, lubrication, types of oil pumps, carburetion and mixture requirements, Brake Mean Effective Pressure and air flow.

This is the intro. Carburetion has its own chapter, as does exhaust pipes, cylinder head and valve train, transmission clutch and final drive, ignition, and turbo charging, supercharging and nitrous oxide.

The second half is on getting that power to the ground. Chapter thirteen is on how suspension works, with the basics of spring rate and bump isolation, attitude change, damping and linkages.

Then comes a section on configuring your suspension within the stock parameters, with diagnostic information.

Cameron's years in the game show in his little bits of history, like changes in weight distribution of motorcycles over the years. An anecdote:

Ducati's 750 towershaft twins, with the engine weight set so far back, had too little weight on the front tire for good stability with quick steering geometry. Therefore, to make stability adequate, the front end was raked out to a huge 31 degrees, with 4 1/2 inches of trail. This made the steering heavy and slow, even with little weight on the front tire. Some will argue that this was done in ignorance, but history shows that the nuimble single-cylinder 350 and 500 racers of the 1950s and 1960s were often given steerng-head angles of 24 degrees or even less by private tuners. The value of quick geometry was well known by professionals, but production bikes were given heavy steering as the easiest way to prevent high speed instability. At the time, this heavy steering was praised as giving the feeling of "being on rails". What that phrase really meant was that these bikes steered like railroad locomotives, which actually were on rails. They just followed the tracks and could not be steered, once committed to a line. High stability means high resistance to being deflected by any disturbance - even one caused by the rider's efforts to steer.

And more, from the chassis chapter:

In 1993 Yamaha redesigned its 500cc GP chassis to be stiffer than ever... When this chassis was practiced at the Australian GP, it would not hook up. As rider Wayne Rainey said at the time: "we have chatter, we have hop, and we have skating."

This outcome had been predicted by English chassis-dynamics researcher Geoffrey Rowe. He had noted that, when leaned over, a motorcycle's suspension becomes less and less useful, as the bumps act vertically, but the suspension operates only at the lean angle. At present, with lean angles of the order of 60 degrees, suspension would have to move more than two inches to fully absorb a 1-inch step in the road. Chassis flex, Rowe noted, is the silent partner of the movable suspension. Fork-tube bending, steering-head twist, and swingarm deflection absorb a multitude of small bumps. Yamaha had finally made its chassis so stiff that it could no longer absorb such bumps, which were then kicking the tires loose in "chatter, hop and skating".

Cameron follows with chapters on tyres, wheels, brakes, oils, fuels and weight reduction, and finishes at chapter 22 - "Upgrading Yourself". Your bike's probably better than you are already, and improving your skills and fitness will most likely help you ride faster than spending money on your bike.

Top of my bike tech-nerd collection is Tony Foale and Vic Willoughby's Motorcycle Chassis Design. Kevin Cameron's Sportbike Performance Handbook is going right next to it. And, in fact, it's very similar in style and content. Clear and simple descriptions of cutting-edge theory, history, practical examples and tales from the front, and just the thing to absorb that $44.99 that's burning a hole in your pocket.

It's available from all good bookshops.

If your bookshop isn't a good bookshop, they can probably become one by emailing Capricorn Link Australia: books (at) capricornlink.com.au and telling them to supply a few copies of Sportbike Performance Handbook.

Tout de suite.