2008 Buell 1125R


lo-band | hi-band
The recent unveiling of Buell's all-new liquid-cooled V-Twin superbike sneaked up on most everyone, but the cry for such a machine from Buell has been in the wind for years.

"If only it had a modern, liquid-cooled engine," was often the plea of so many who would characterize their thoughts on Buells as, "I wanna like you, buuut..."

Has a partnership with BRP-Rotax given Buell lovers and those vacillating on a purchase what they've clamored for?

As fate would have it, in the matter of one phone call I went from pondering the above question like everyone else to seizing the opportunity to attend the 1125R intro. The much-chronicled roads surrounding Monterey, CA, would serve as real-world proving grounds, and Laguna Seca, home of the U.S. MotoGP would be the race track du jour.

The 2008 Buell 1125R: America's first large-scale production superbike?
Analog tachometer is easy to see at a glance, but the remaining LCD part of instrument cluster can be difficult to read in daylight due to thin LCD character display.
In case you didn't get a chance to read our Buell 1125R First Look in early August, we'll go over some of the specs here. Developed in conjunction with BRP-Rotax, makers of the 998cc 60-degree V-Twin engine in the Can-Am Spyder as well as a similar motor found in modern Aprilias, Buell specified an 1125cc liquid-cooled fuel-injected 72-degree DOHC eight-valve V-Twin as the heart of the machine.



So why choose 1,125 cubic centimeters resulting from the oversquare 103mm x 67.5mm bore and stroke? According to Buell, these dimensions produce the best marriage of broad, available torque and horsepower. Compression ratio is 12.3 :1.

Equally as uncommon today is the 72-degree angle. Abe Askenazi, Director of Analysis, Test and Engineering Process, stated that Buell is aware that a 90-degree Vee has better primary balance, but 72-degrees proved ideal for the best gas flow path as well as being a more compact design. Engine vibes were anticipated, so three balancers were employed (two to cancel primary rotating imbalance, the third canceling out rocking couple).


Not all the buzz has been eliminated, as you would expect from a rigid-mounted engine serving as a stressed member of the chassis. The remaining vibes are palatable, never really impacting comfort or performance. Coincidentally, the tach needle does suffer in an amusing manner. As it reaches the upper rpm range, it appears to be resonating at such a rate that it "grows," blurring your reading over roughly a 500 rpm span. Not a problem, really, just kind of funny.

Since this engine is a clean-sheet design, it has some unique features. For example, the process of opening and closing the 41.3mm intake and 35mm exhaust valves. A self-adjusting cam chain drive and gear operates the intake cam that in turn meshes with a gear on the exhaust cam. Finger followers (more often found in automotive use, especially with Less bits mean less material to spin around which, in turn, should equate to a faster motor.variable valve actuation systems) are used instead of more traditional tappets. Acting directly on shims over the valve, the follower's linear movement eliminates the need for buckets. Less bits mean less material to spin around which, in turn, should equate to a faster motor.

But it doesn't end there. Are you a do-it-yourselfer? Buell hasn't forgotten about you. After rotating the engine forward a bit you can remove the magnesium valve cover and access a simple plastic clip that retains the finger followers. Slide the followers to the center and you're grabbing at those V-Rod spec shims in no time, about every 12,400 miles. This is, of course, an abbreviated version of the work involved, but as someone who has done countless valve adjustments I can really appreciate this.

Capitalizing on the unused resource of vacuum in the manifold generated by the massive 61mm throttle bodies, Buell came up with its version of a back-torque-limiting clutch, similar again to the Aprilias. Just inside the outer clutch cover you'll find the usual hydraulic slave cylinder and a big diaphragm. A simple tube or hose connects the manifold to the outer cover. Separated from the clutch that's thrashing around in oil that could potentially ruin sealing, the diaphragm gets pulled outward against the clutch-release mechanism when the throttle is fully closed, or roughly three percent open. This creates enough vacuum to relieve pressure on the clutch to keep it from fully compressing. Any greater throttle openings create low vacuum and the clutch stays tightly clamped.