Buell Factory Racepipe
BUELL FACTORY RAGEPIPE
CW EVALUATION
Bolt-on pavement peeler
BIG CYLINDERS EQUAL BIG INTAKE AND exhaust pulses. That simple fact explains why big Twins need big airboxes and mufflers. And even with volume, engineers sometimes have to make trade-offs for Twins to pass noise tests that they’d prefer to avoid.
That’s certainly the case with Buell motorcycles. Big, ugly mufflers allow these machines to make almost as much peak power as they would with an open pipe, but even so, the internal resonances that cancel certain noise frequencies wreak havoc on the torque curve elsewhere. For the S3 Thunderbolt, as an example, that translates into a 49.3-foot-pound torque reading at 3000 rpm, a huge drop from the 60plus foot-pounds made a few hundred rpm before and after.
Fortunately, you can buy a system engineered by the factory without worry about noise or exhaust emissions: the $553 Buell Racepipe,
for “closed-course use only,” of course. Consisting of a new header with longer exhaust pipes meeting in a big, 2.5-inch collector and a matching aluminum-bodied straight-
through muffler, this system was designed by the same team that drew up the stock pipe, but with power its only priority.
We tried one on a Thunderbolt in conjunction with two other changes: a Buell racing ignition module ($115), supplying the same ignition curve as stock without the retard that normally starts at just past 6000 rpm-still retaining a 6800-rpm limit-and a bump in pilot jet size to a #48. Installing the pipe was straightforward, requiring only a couple of hours in total, and the ignition module went in place in mere minutes. Getting the pilot jet in place took almost as long as the pipe, requiring removal and replacement of the Buell’s incredibly complex airbox. But the results were exceptional.
With pipe in place, torque jumped upward almost everywhere, from a mammoth 14 ft.-lb. increase at 3000,
to a 9 ft.-lb. leap at 4000, to a 5 ft.-lb. movement at 6500. Midrange was solidly boosted, with the torque peak coming in stronger earlier, 76.3 ft.-lb. at 4500 rpm instead of 71.8 at 5300.
Peak power increased from 75 horses at 5800 rpm to 78 at 6300, with power hanging in at more than 77 horses until past 6500 rpm. To summarize: a near-ideal improvement, with lots more torque down low and a little more power up high while revving out longer.
The power increase was enough to improve quarter-mile times from 12.19 seconds to 11.90 seconds, while roll-ons dropped to 3.8 seconds for both 40-60 and 60-80 mph. But riding the bike was most telling: The increase in acceleration and responsiveness was sufficient to change the S3’s personality from a slightly pale underachiever to a vividly crisp accomplice in slightly uncivilized behavior. Wheelies come easily, throttle response is immediate, and all is accompanied by a deep basso rumble that’s loud without being as annoying as most Harley pipes or some aftermarket mufflers intended for Buells. Consider it one of the most successful single performance improvements available for any motorcycle. □
