Buell XBRR

 

 

 

 

I had the opportunity to work alongside the teams campaigning the radical new 2007 Buell XBRR at Daytona last month and what an eye opener it was.Erik Buell has long been credited for building unique motorcycles that truly show the ability to think outside the box.Are these ideas right, wrong, or just different?Some of the designs that make this motorcycle truly unique, are definitely engineering feats, some may even say oddities.The first difference you notice when looking over the Buell, is the placement of the fuel in the frame.On the upside, it is a very clever use of available space.To make the capacity large enough to be valuable to the racer as well as the street consumer, the frame spars are definitely maximized in their dimensions.This large hollow frame with the huge areas visible around the steering head and running down to the swing arm area must be tremendously strong and rigid, benefiting chassis handling and stability.Finally, the fuel is carried much lower and closer to the bikes centre of gravity to minimize itís effect on handling during fast transitions.Downsides?The airbox volume is definitely compromised with the wide frame spars, as well as the distance from the throttle bodies to the airbox lid above it where the fuel tank would normally sit.The engine, with its narrow V angle, definitely restricts the size and height of the airbox anyway regardless of where the fuel is placed, so there isnít much getting away from this one.The only other downside to the fuels placement is more important on a race bikeís performance than on itís street cousin, and that is the fuelís tendency to heat saturate.The frame and even the swingarm on a V twin race bike historically gets unbelievably hot during a race, as I remember the works Honda RC51ís campaigned to great success around the turn of the century (that still sounds funny) could burn your unprotected hand or leg if you werenít careful after a track session.A conventional fuel tank has complete rubber mounted separation from the frame and two degrees of separation from the engine, to insulate it from the engineís heat.Donít get me wrong, left alone on a hot bike sitting on the grid after a warm up lap, the fuel in a conventional tank can still get hot, but the heat rolling up from the right (exhaust) side of that Buell after it came off the track is incredible.

 

Another Buell trademark is definitely the perimeter mounted front brake rotor.In Erikís ongoing pursuit of performance, he is incredibly weight conscious, a very commendable trait.If there is one place that a weight reduction shows many benefits, it is in the wheels, and man those Buell wheels are light.In talking with most of the riders, they all seemed to echo the fact that the brakes had incredible initial bite, but then as you held them on, they lacked the outright power of a conventional system.Is the brake system better than a conventional single sided disc?For sure!Is it better than a conventional two disc system No one is sure yet.In having a look at the pads after a practice session, they have definitely taken a pile of heat, but this is Daytona, and all brakes take a beating here.There was talk of ongoing brake pad testing for future venues, and that may cure the Ďpowerí concern, just leaving the benefit of the huge weight savings.

 

The other design feature unique to the Buell is the oil in the swingarm.The Harley uses a dry sump engine, which lacks the conventional oil pan found under most engines.This oil is kept away from the motor and pumped in during operation and pumped out to reduce viscous drag.Is sloshing around in the swingarm the best place for this oil?As with the fuel, it is again a clever use of space, but what of the weight added to the unsprung suspension equation?Another concern is heat added to the oil in the swingarm.On an inline four-cylinder engine configuration, the swingarm can get quite warm as it absorbs a bit of heat from the frame, (which is helping radiate the heat away from the engine), and it absorbs heat rolling back as hot air from the rad and engine cases.A V-twin motor sees this same heat absorption, plus has a cherry hot exhaust header pipe merely inches away from the front of the swingarm and in some cases; this exhaust header even passes through the swingarm.So, you can imagine just how hot a swingarm can get on a typical V twin, which begs the question is this the best spot for the engine oil to cool down?In discussions of the drive train after the 200, Erik had indeed been monitoring engine oil temperatures and is definitely on top of the situation.In a related discussion of weight on the swingarm, Erik has chosen to not run a Cush drive on the XBRR.His reasoning was an effort to save the 1-1.5lbs associated with the Cush drive casting and extra bearing required.The race bike however, no longer runs the rubber belt drive of its street cousin and utilizes a conventional steel drive chain.So, in this pursuit of weight reduction on the wheel and traditional gearing opportunities (chain and sprocket) the bike has lost much of itís ability to absorb the tremendous torque impacts from the V twin engine.Perhaps a cush drive installed would go a long way to help the drive trainís durability?Who knows?I discussed this with Erik, but he felt that the springs located in the back of the clutch basket (common to most bikes) was sufficient to absorb this shock.

 

One thing is for sure; the Buell is a quick turning, fairly light, groundbreaking motorcycle with tremendous potential just ahead of it.With an estimated 140 rear wheel horsepower and 100 ft.lbs of torque, Buell could overturn the Japanese applecart in the highly competitive AMA Formula Extreme class where Factory hopped up 600ís scream to 16,000 rpm and make power in the 130 horse power range.Stay tuned, this American made bike with super talented riders like ex Moto GP rider Jeremy McWilliams and multi time Canadian Champion Steve Crevier is heading for the podium and soon!††††