Buell 1125 R

Dailies. Galleries – September 20, 2010

Looking like something that H.R. Geiger found in the bowels of an alien vessel, this experimental prototype was created by a German race team to further the competitive development of the Buell 1125R in the immediate aftermath of Harley killing Buell. Some of what they learned here is paying dividends in the Sound of Thunder Championship, where the team’s Buell 1190RR -Bs have secured the championship before the season has even finished.

This project began shortly after Buell was shuttered and before Erik Buell Racing was announced. Team owner Thomas Wanner says, of facing a decision on how to continue racing after last fall’s announcement, “We decided to go racing in 2010 for sure, so something needed to be done to continue the development of these bikes.”

At the time, there was no 1190RR, so Pegasus — which had been racing Buell’s since 2001 — had to find ways to develop the 1125R platform. The project set out to explore ways to improve the weight, weight distribution, riding position, ergonomics, engine air supply, radiator airflow, aerodynamics, power, front brake cooling and even the bike’s crash-ability so it’d make a better endurance racer. Essentially, they were setting out to re-invent the 1125R.

Perhaps the biggest alteration was the fabrication of a carbon monocoque frame. “The carbon parts are produced in house and we are surely not a carbon manufacturer, its ok for us to find out if it works and to set some standards in weight and stability, but please don’t judge us for the looks,” explains Pegasus’s Jens Krüper. “It would be simple to fill and paint it, but the job was nto about ‘customizing,’ it was more important to prove if a monocoque with a little subframe could do the job and it dropped the weight 3.7lbs.”

The carbon fiber components drop the overall weight of the bike 3kg/6.6lbs, to 167kg/368lbs without fuel.

Experience racing the 1125R prior to last October suggested that one of the first alteration made to the bike need to be to the rider position in order to improve the weight distribution. To achieve that, this experimental 1125R re-positions the rider 70mm rearwards. The Buell 1190RR, itself a development of the 1125R, would also adopt this change, with a 60mm rearward shift.

The new riding position also made it possible to fit a 40-liter airbox under the faux tank.

Jens describes the new riding position as, “moved from sitting in the bike to sitting on the bike, like on all other modern racebikes, contributing to the bike control you need for real fast laps.”

The next modifications were to find relatively easy ways to improve engine breathing. Obviously this is achieved through improving the intake and exhaust paths. Due in part to the 1125R’s fuel-in-frame arrangement, it’s inlet tract original passed below the triple clamp, then made a 90-degree turn to reach the airbox. Not ideal.

To fix this, the team adopted a solution similar to that of the Buell XB-RR race bike, running air inlets over the bars and into the top of the “tank.” Riffing on Erik Buell’s mantra of using single parts to serve multiple functions, these air scoops now form the support for the front fairing, instruments and fluid reservoirs. As you can see, the intake was also moved to the front and center of the fairing, the point of highest pressure for maximum possible airflow.

“We learned to blow up woven carbon socks in a mold to get this shape and, in the end, we got a very strong and light part that presses the air from the area of highest pressure on the fairing nose direct into the airbox, where we mounted a foam/air cleaners ystem with some special stacks,” says Jens.” In addition to saving weight and improving airflow, this arrangement should also prove more rugged than the stock magnesium brackets, which are prone to snapping in a crash.

The 2-1 bellypan-mounted exhaust uses EBR headers for improved gas flow, but adds 860mm of perforated baffles inside to reduce noise levels. This improves power over the stock exhaust, but still meets stringent new 104dB noise limits being imposed on club racing in Europe beginning next year.

Buell 1125 R

The engine is untouched aside from the improved inlet and exhaust tracts and the addition of an ECU tuned to exploit them. The end result of these modifications is 137hp at the rear wheel. Considering the stock bike is quoted as 140bhp at the crank, that’s nearly a 10-15 percent improvement.

Next up was aerodynamics and airflow through the 1125R’s controversial side-mounted radiators. Radiator efficiency was one of the chief mechanic issues tackled by the 1125R-based Magpul Ronin that we exclusively unveiled back in March. Unlike that bike, the Pegasus prototype keeps the stock radiator locations, but reverses the air flow through them.

Cool air is now drawn from beneath the triple clamp at the front of the bike, passes through the radiators and is then drawn out by the “gills.” Those modifications make the 1125R 90mm (3.5 inches) narrower, which also helps improve aerodynamics.

Further aerodynamic efficiency was gained by increasing the height of the screen to better protect the rider. Like the 2010 MotoCzysz E1pc. the Pegasus prototype acknowledges that the greatest hurdle in reducing drag isn’t necessarily frontal area, but improving the re-connection of the airflow as it leaves the bike.

To achieve that, the bellypan has been lengthened and smoothed out and the hugger encloses as much of the rear tire as possible while the tail unit has also been slimmed down and lengthened. Check out the way the bellypan/hugger combo nearly encloses the swingarm on the left side.

Other modifications include an airscoop intended to direct cool air towards the ZTL brake’s single caliper and a brake fluid cooler mounted underneath the engine.

Pegasus intends to make the bodywork seen here available to other race teams in the near future and plans to campaign two additional racers based on this prototype in the Sound Of Thunder series next year.

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Buell 1125 R
Buell 1125 R
Buell 1125 R
Buell 1125 R
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