The Buell 1125R was the American company’s first full sport bike with a liquid-cooled engine. Introduced in July 2007 for the 2008 model year, it used a 1,125 cc 72° V-twin built by Rotax in Austria instead of the air-cooled Harley-Davidson derived motors that had powered every Buell before it.
Buell 1125R at a glance
| Maker | Buell Motorcycle Company, United States |
|---|---|
| Production | 2007–October 2009 |
| Engine | 1,125 cc Rotax Helicon 72° V-twin, liquid-cooled |
| Claimed power | 146 hp (109 kW), rev limit 10,500 rpm |
| Measured power | 127.1 hp (Motorcycle Consumer News), 134.0 hp at 9,800 rpm (Cycle World) |
| Top speed | 158–161 mph (254–259 km/h) |
| Quarter mile | 10.39–10.51 seconds |
| Front brake | ZTL2, single 375 mm perimeter rotor, eight-piston caliper |
| Frame | fuel carried inside the frame |
| Final drive | toothed belt |
| Tyres | 120/70ZR-17 front, 180/55ZR-17 rear |
History of the Buell 1125R
The 1125R was presented in July 2007 and went on sale for 2008. Its engine was a completely new departure: the Helicon V-twin of 1,125 cc was made by BRP-Powertrain (Rotax) in Austria, with final assembly in Wisconsin. Liquid cooling allowed a 72° V angle and a rev limit of 10,500 rpm, quite unlike the 45° air-cooled Sportster-derived twins Buell had used until then. Buell claimed 146 hp; the magazines that tested the bike recorded between 127 and 134 hp at the rear wheel, with a top speed around 160 mph and quarter-mile times of about 10.4 seconds.
The chassis followed Buell’s ideas about mass centralisation. Fuel is carried inside the aluminium frame, the exhaust runs under the engine to keep its volume low and central, and the front brake is a single ZTL2 unit with a 375 mm inverted rotor bolted directly to the rim, gripped by an eight-piston caliper. Mounting the brake at the rim rather than at the hub let Buell build a lighter, more responsive front end. A toothed belt replaces the usual chain, so there is no lubrication or adjustment to do.
For 2009 Buell added the 1125CR, a naked version that borrowed the R’s engine and chassis but was heavily reworked, and the improvements were later carried back to the 1125R. Production of the 1125R, and of every Buell model, stopped in October 2009. In November that year Erik Buell founded Erik Buell Racing, which at first built race-only versions of the 1125R.
Design and features
- Rotax Helicon engine: a liquid-cooled 72° V-twin of 1,125 cc, the first water-cooled motor in a Buell.
- Fuel in the frame: the patented frame doubles as the fuel tank, lowering and centralising mass.
- ZTL2 perimeter brake: one 375 mm rotor fixed to the rim with an eight-piston caliper.
- Under-engine exhaust and belt drive: more volume in less space, and no chain maintenance.
Buell 1125R versions
- 1125R (2007–2009): the fully faired sport bike.
- 1125CR (2009): a naked version with the same engine, heavily revised and later feeding changes back to the R.
- Erik Buell Racing racers (from late 2009): race-only 1125R-based machines built after series production ended.
The 1125R sat above the air-cooled XB12 and XB9 models in the range. More Buells are in the Buell collection.
Video: Buell 1125R (2009) Stock Exhaust to Jardine RT-5
Video by T H (Blue04SRT4) on YouTube.
Sources
- Buell 1125R, English Wikipedia: specifications, tests, design
- Buell 1125R, Italian Wikipedia: production dates, 1125CR, tyres
