Wisconsin's Road America (RA) raceway is a very long, very fast circuit--4.1 miles, with three long straights. So when Buell announced the release of its new XB12-series bikes--with 1203cc V-twin engines--would take place at
RA, we were understandably excited. What better place to get acquainted with a bigger-balled Buell than Road America?
As it turned out, we sampled the XB12R Firebolt on a shorter (two-mile) configuration that concentrated action on the more technical back half of the course (for reasons that would later become clear). We also rode the XB12S Lightning streetfighter (a Firebolt with lower pegs, a tubular handlebar and fly screen instead of a quarter fairing) on RA's Motorplex, a diabolically difficult, 1.1-mile mini road course built expressly for go-kart and supermotard racing.
The Motorplex squeezes 16 turns (some downhill and off-camber) into a little over a mile, and is so tight that you run the entire track in second gear (excepting a quick shift to third on the short, 80-mph front straight). On most bikes this would mean boggin' then bumpin' the rev limiter--not so on the new XB12s. The engine is basically a stroked XB9 mill (88.90mm x 96.82mm bore and stroke; and yes, those figures are identical to the 1200 Sportster), and as you might expect from such numbers, these are torque-heavy beasts: 78 foot-pounds at 2500 rpm, Buell claims, peaking at 84 foot-pounds at 6000 rpm.
This single-gear samba also played to Buell's excellent, zero-lash belt final drive. No worries about getting on the gas early because the power delivery is completely drama-free.
A good thing because staying on the throttle through the corner is essential in order to ride the Lightning quickly. Just 52 inches between the axles, with an extremely low, forward CG ("Mass Centralization" is Buell's design priority), the Lightning is a breeze to steer at low to moderate speeds. But once you up the pace, the XB12S shows the same disconcerting tendency as the XB9S to stand up under braking, then fall over once the binders are released. Trailing throttle through the corner (to balance the suspension and unload the front end) helps. Hanging waaay off to reduce lean angle also made the push and flop less pronounced. You can ride the Lightning quite fast (we were just a few seconds off the best motard times, remarkable for 400-pound bikes with street tires), but it's not easy.
Funky behavior was less pronounced on the Firebolt. Contrary to what you might expect from a motorcycle with such radical chassis numbers, the Firebolt is remarkably stable--even at full lean through RA's Carousel, where you're knee-down and on the edge of the tire all the way through fourth gear.
On the big road course, the pumped-up midrange of the XB12 engine is immediately obvious, and the bike accelerates with authority at any rev. Extra cubes equal extra beef, but credit for the linear power delivery must also go to Buell's new "Interactive" exhaust valve (exclusive to the XB12s) that toggles between two muffler-flow paths to keep the torque curve steady across the rev range.
Even with the two long straights deleted, there was enough distance through the Kettle Bottoms to pull redline in top gear, for an indicated 139 mph. Gear ratios in the five-speed transmission remain the same as those in the XB9, but the primary-drive ratio has been lowered from 1.68:1 to 1.50:1.
Like the XB9, shifting the XB12 is a slow, deliberate process. Stiffer clutch springs are fitted to the XB12s, making what was already a high-effort lever even nastier. Clutchless upshifts are hopeless. Fanning the clutch is similarly ineffective--even at high revs the XB12 demands that you engage the clutch completely, shift authoritatively and ease the lever out slowly.
To be fair, the racetrack isn't the best place to evaluate the $10,995 XB12s; the Firebolt and Lightning are both explicitly advertised as "back-road bikes," a more diverse milieu where Buell's utterly unique combination of traits might make it a viable big-bike killer. Unfortunately, because we rode these bikes a month before their official release to the public, we weren't able to venture out on the street. A proper (and more relevant) street impression will have to wait until a tester appears in our garage.
Type: a-c 45-deg. V-twin
Valve arrangement: ohv, 4v
Weight: 395 lb. (claimed, dry)
Fuel capacity: 3.7 gal.
Wheelbase: 52.0 in. (1320mm)
Seat height: 30.5 in. (775mm)