Reader Essay

One of your competitors just jumped on the global-warming bandwagon and ran an issue devoted primarily to electric motorcycles, including electric bikes in racing. While electric motors are the "current" rage, few are addressing the weight, expense, toxicity and short life of today's battery technology and the utter impracticality of an electric vehicle.

As for electric racing, I can't think of a quicker way to kill the sport. Motorsports competition is about the skill, the strategy, the speed, the shriek of the engines and the smell of spent racing fuel! Go to Laguna Seca or the Indy Motor Speedway to hear the whirr and whizz of DC motors and catch the scent of ozone in the air? Definitely not. As of yet, there is no practical substitute for the internal-combustion engine, especially in motorsports.

I propose you guys take a different tack on the current Green rage and do a story or two on alternative fuel use in current

Rainey and Kevin Schwantz were there, as well.

Hearing the bike fire up and watching KR's hot laps made me grin from ear to ear! I didn't get to see it live in '75 but this had to be the next best thing. Mark Roberts

Lexington, Illinois production motorcycles. Swift Enterprises (www.swiftenterprises.net), a company in Indiana run by a Purdue professor, has developed a fuel that can replace 100-octane leaded aviation fuel and is presently being tested in piston-engine aircraft. It is a 104-octane brewed from sorghum and could be produced from switchgrass, garbage or any number of other materials that are not normally cultivated for human consumption. Unlike ethanol, it doesn't consume food staples like corn or sugar cane, and it has no ill effects on fuel systems.

You could run the numbers for a highperformance bike on standard racing fuel and then switch to the Swift fuel. Maybe a long-term test, as well, with two bikes, one running conventional gasoline, the other on Swift fuel, with a teardown after 50,000 miles or so? C.W. Whitby

Prescott, Arizona

KTM corner

Congratulations, Blake Conner, for your excellent test on the KTM 990 Adventure (CW, September), and to Jeff Allen for the astounding pictures. I am big trailie lover myself, owner of a 1997 Triumph Tiger, and a photographer, too, far away from you guys in the south of Brazil-Florianopolis, on Santa Catarina in the Atlantic Ocean, land of the most beautiful women in the world... sorry. Rui Bittencourt

Posted on www.cycleworld.com

Would you like to trade your KTM Super Duke long-term testbike for my 2000 Bimoto DB4? Kirk Dequila Posted on www.cycleworld.com

Throw in airfare to Florianopolis and it's a deal... Q

Throw in airfare to Florianopolis and it's a deal... Q

Tip-Toeing Through the Tulips

Kevin Cameron

Through the years 1975-2001, when two-strokes dominated 500cc roadracing, the high power and steep powerbands of those engines forced the development of capable chassis, suspensions and tires. Those emerging technologies, combined through the 1980s with compact and lightweight liquid-cooled four-stroke engines, made the modern high-powered sportbike possible. Even with mufflers, lights and dual seats, these bikes were more capable in every way than pure racebikes of just a few years before. Talk about leveraging your synergies!

A fresh cycle of revolution began in 2002 with the idea that racing motorcycles should cease to be their riders' enemies and instead become their allies. There had been efforts to implement improved rideability with two-stroke 500s but the results were mixed at best-like putting a comfortable saddle on a saber-toothed cat. The first tool in the new MotoGP revolution was the same one that had made high-power sportbikes rideable by average riders-smooth, predictable torque curves that were easy to use, free of traction-destroying surprises like flat spots closely followed by torque spikes.

This was refined in 2003-05 by track-

side ignition mapping, in which riders and tuners could themselves smooth particular problem areas of an engine's torque curve by programming in local ignition retard. Next came a period in which electronic traction-control systems were the focus.

Now we live in the era of so-called "virtual power." Rather than shaping the engine's actual torque curve with cams, pipes and ignition settings, this concept uses rapid, computer-directed movements of the engine throttles to generate a smooth torque curve. This concept has long been the way things are done in Formula One. The more power an engine is made to give by such means as long cam timings and sharp intake and exhaust tuning, the less smooth its torque curve becomes, and the harder it is to use by driver or rider.

Virtual power simply interprets the rider's throttle position as a torque demand, which is then achieved as the engine accelerates by rapid computer-driven movements of the throttle plates. As the engine passes through a flat spot, the throttles open to compensate, filling in the hole. As torque hits a spike, the throttles close enough to keep torque constant. The engine's natural torque curve may be bumpy but what is delivered to the rear wheel is smooth-as close to the rider's current torque demand as possible. with this smooth, predictable torque, the rider gets strong, hard drives off every corner, with none of the slip-and-grip highside histrionics of the old 500 two-strokes. Virtual power can work only at part-throttle, but a racing motorcycle does most of its important business in that condition.

That is the ideal. But in a conversation at the Indianapolis MotoGP event with Suzuki crew chief Stu Shenton, I learned that reality often differs from that ideal. F-1 cars, he noted, have powerful hydraulic actuators to operate their throttles. MotoGP bikes are prohibited by rule from employing hydraulic power, so their throttles are actuated by a slower technology: stepper motors. Hydraulic servo-valves, derived from aircraft flight controls, are capable of operating at very high rates, but stepper motors are more limited.

This means that if the rider is smooth and the engine's natural torque curve not too bumpy, the stepper-controlled throttle can do a fair job of producing smooth virtual power. But if the rider is very aggressive with the throttle, or if the base engine is highly tuned, the

MotoGP is a chancy business in more ways than one. Chris Vermeulen is off the Rizla Suzuki for 2010 and currently shopping his services.

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