Sexy Beast

Few people would consider an exotic like Bimota's SB6R as good grist when building the Ultimate Custom Sportbike. After all, Bimotas are too expensive, too rare and, well, too damn foo-foo "eye-talian" to hack apart and transform into a true, in your face hyper bike, right?

Not according to Barry Henson, well-known AMA Prostar drag racer and owner of the too-trick SB6R pictured here. Henson is also the man behind Velocity Racing in Davie, Florida, home to some of the fastest turbocharged motorcycles in the world. When he set out to build his dream streetbike, the Bimota was an obvious choice.

"This was going to be my personal bike for me to ride on the street, so I wanted a roadrace-style bike that was agile and handled well," Henson says. "But I also needed a motor that could handle big--make that really big--horsepower. The SB6R has a liquid-cooled GSX-R1100 motor, and I knew from my dragracing experience that it could handle all sorts of power. I started this project in 1998, before the Hayabusa or the GSX-R1000 were out, so the SB6R with the big motor in the Bimota frame was the only choice."

Henson bought the bike brand new from a local dealership--for $23,000--and after a short break-in period he got down to business. Serious business. "I put 500 miles on the bike, and then I gutted it like a pig, tearing it completely down and starting over from scratch," he says.

Henson tackled the chassis first. Bimota is well known for its excellent framesets, and lightweight, rigid racks the company outfits with the most sophisticated powerplants from Japanese and European manufacturers. But the 135-horsepower produced by a stock GSX-R1100 engine is a long way from the 450-plus-hp rating that Henson envisioned for this bike, so certain changes needed to be made.

The first step Henson took was to improve clutch access on the right side of the frame. In stock form, you actually have to drop the engine out of the SB6R frame in order to access the clutch--inconvenient on high-horsepower bikes that like to eat clutches. So Henson made a half-moon cut in the right main spar of the chassis, then modified the clutch cover to allow the clutch pack to be removed without dropping the engine. Henson fabricated a billet chunk to fill the area around the half-moon cut and welded it up, actually making that section of the frame more rigid than it was before.

Once the structural mods were completed the frame went on a diet, and Henson shaved off all inessential brackets and hangers. The swingarm was sent to Coby Adams, who modified it with slotted ends to allow six inches of adjustment. When that was complete, the frame and swingarm were both shipped to Henson's friend, Tom Rutterer, who applied the mile-deep black paint.

The Bimota-spec Paoli fork was disassembled and stiffened, and the triple clamps were tended to, also. The upper and lower triple clamps were cleaned up, and the lower one strengthened--"because it just looked weak to me," Henson says. Out back, Henson runs an Oehlins shock (not the original), also revalved and fitted with a stiffer spring. The bike is lowered at both ends, but not much--less than an inch--because Henson wanted to maintain cornering clearance and rideability.

All of these elaborate chassis mods make sense once you consider the engine Henson built for his beastly Bimota. Henson made his name with pumped-up turbo engines--he built the 500-hp engines that power his and teammate Kent Stotz's matching Honda CBR1100XX Streetbike Shootout drag racers, after all--and the motor in his SB6R more than maintains this reputation. Henson started by strengthening the internals, replacing stock Suzuki parts with a Falicon crankshaft and rods, JE turbo pistons (9.5:1 compression ratio), and a set of Yoshimura drop-in cams. Henson also opened the cylinder head, fitting 1mm-larger valves on both the intake and exhaust sides.

All these mods were made in preparation for the custom-crafted turbocharger system, Velocity Racing's specialty. The turbo unit itself is a hybrid of Garrett T03/T04 parts (assembled by Henson) feeding into a one-off fuel-injection system with 42mm throttle bodies built to Henson's specs by Kinsler Fuel Injection Systems. "I have to give big props to Kinsler--the fuel injection worked flawlessly right off the bat," Henson says. A fully programmable MSD ignition allows Henson to easily roll the timing in or out depending on his tuning needs.

Look carefully at the plumbing of the turbo system and Henson's abilities as a fabricator become immediately apparent. Packaging in the compact SB6R chassis is tight, and the gas tank runs particularly low and close to the engine, which led to some unique problems making room for all the bits--"the old 10 pounds of crap in a five-pound bag," Henson laughs. The battery, formerly located in front of the engine, has been relocated beneath the seat to make room for the turbocharger itself. And Henson had to actually split the intake plenum into two separate, smaller pipes routed over the engine because there wasn't room between the bodywork. After all this, fabbing up a custom stainless exhaust system (exiting through Micron carbon-fiber canisters in the stock underseat location) was a breeze.

When it came to the rest of the bike, Henson spared no expense. All the hardware is titanium, the brakes and rotors were replaced with Brembo GP-spec parts, and the wheels are featherweight Marchesinis with a custom spacer kit to fit the SB6R. The bodywork is factory Bimota, all carbon fiber, with original paint because Henson didn't want to cover up the bare carbon bits. But the coolest feature is the digital dash/datalogger that fills the fairing. Made by Pi Research for Formula Atlantic racing cars, this $6000 unit monitors sensors on the front and rear wheels, as well as a handful of engine sensors to allow Henson to track every last aspect of the bike's performance.

Henson is uncertain of the bike's actual power output in its present state. The last time the bike was on a dyno it put down 475 hp, but the engine has gone through some changes since then. That 475-hp number came through an intercooler, but just days before these pictures were taken Henson removed the intercooler and replaced it with Velocity Racing's new and more-efficient water-injection cooling system that was perfected on Henson's Shootout racer. "Before, I was limited by how much air I could flow through that intercooler," Henson says. "I'm excited about getting it back on the dyno now without the intercooler. It should make well over 500 horsepower." Removing the intercooler will also lighten the bike slightly, improving an already excellent power-to-weight ratio. The last time Henson weighed the bike it tipped the scales at 410 pounds (wet)--just one pound more than the dry weight of a stock, nonturbo SB6R.

Henson has never had his Bimota on the track, though he says it's the fastest streetbike he's ever ridden--and he's built and ridden some of the fastest in the world. Henson has taken the bike "nine-tenths" racing--an underground thing that Henson and other hyper-bike enthusiasts get together for every Sunday morning on an arrow-straight, nine-tenths-of-a-mile-long stretch of deserted highway in the middle of Florida's Everglades. Henson has had the Bimota up as high as 218 mph in nine-tenths racing, but was plagued with clutch problems at the time. Henson reckons that, with the intercooler removed and the clutch sorted, his Bimota will do around 240 mph!

But remember, this bike was built to be Henson's street machine, and as such, it is fun at lower speeds, too. For instance, Henson says wheelies at a mere 160 mph are "effortless." Sound fun?

"It's a sick bike, it truly is," Henson says. He said it, not us.