Buell 1125R 2007-2010 Service Manual

Motorcycle Daily's own first-ride account from the press launch captures the genuine engineering ambition Buell put into this new engine, straight from the source: "at the press intro for the Buell 1125R, I spoke extensively with a senior Rotax engineer about the new Buell's engine, and the words 'state of the art' came out of his mouth so often, I began to think he had a strange form of Tourette Syndrome." TopSpeed's own retrospective confirms the genuinely unusual development brief behind that engine: "instead of building an engine to a certain size and then seeing what kind of torque and horsepower it produced, Buell started with his specifications for torque and horsepower and told Rotax to build an engine to meet those specs. The result was the 1,125cc Helicon engine."

Power comes from the Rotax Helicon, a liquid-cooled 72-degree V-twin, DOHC with 4 valves per cylinder and finger-follower valve actuation, a 103.0mm x 67.5mm bore and stroke, and a 12.3:1 compression ratio, delivering a claimed 146 crankshaft hp at 9,800-10,000 rpm (127-134 hp measured at the rear wheel) and roughly 71-82 lb-ft of torque, fed through dual 61mm downdraft throttle bodies with a ram-air intake system. Visordown's own first-ride account confirms the genuinely thoughtful engineering baked into this fundamentally new powerplant: "the 1125cc Helicon motor is a 72-degree engine with dual overhead cams and a narrow 14-degree valve angle for improved downdraft intake. The motor also has a hydraulic vacuum assist slipper clutch and a ram-air system. To keep things smooth on the inside, the Rotax-developed motor has three balancer shafts, while to keep things smooth on the outside, 61mm throttle bodies ensure a linear power curve."

Visordown's own review confirms genuine Buell design signatures carried over from the company's earlier Sportster-derived platform, layered onto this brand-new engine: "much of the 1125R comes from the XBRR Formula Extreme race bike, the top fairing comes from the same 'virtual' wind-tunnel, as does the eight-pot rim-mounted brakes... Fuel in frame: check, mass centralization: check, Zero Torsional Load front brake disc: check." Wikipedia's own confirmed specification lists that genuinely distinctive rim-mounted brake as an 8-piston ZTL2 caliper on a single 375mm disc — Buell's signature perimeter-mounted rotor design, a real departure from conventional disc-and-caliper placement, carried directly from earlier Buell sportbikes into this new liquid-cooled platform.

MCN's own review is candid about the genuinely rough edges this bike shipped with at launch: "the Buell 1125R is vastly improved in the six months since its launch in late 2007 but, make no mistake, it is not Japanese or Italian standard in any one area of the bike... vibration can be an issue, depending on what uprated ECU setting is installed – development is still ongoing." Bennetts' own retrospective confirms the genuine ongoing development this bike required after launch: "even at the time of the bike's eventual release in 2008, it still suffered from vibration. This vibration could materialise through the mid-range or at the top end of the tacho depending on what ECU mapping revision was installed – there were constant updates throughout the bike's on-sale period." Grokipedia's own account confirms genuine reliability concerns compounded these teething issues: "electrical glitches, including charging system failures in 2009-2010 models, and high maintenance costs due to specialized Rotax-sourced components were commonly reported."

Suspension consisted of a fully adjustable 47mm Showa inverted fork (120mm travel) and a fully adjustable Showa coil-over monoshock (127mm travel), with a genuine belt final drive and 6-speed transmission. Grokipedia's own confirmed production history places the end of this platform's story in stark context: "Harley-Davidson announced the discontinuation of the Buell brand on October 15, 2009, citing financial pressures from the global recession and a strategic focus on its core touring motorcycle lineup" — the 1125R's production, having begun in 2007 for the 2008 model year, ended in October 2009, with remaining inventory carrying into 2010 sales before the entire Buell brand closed under Harley-Davidson ownership.

This factory service manual covers the procedures, torque specs, and diagrams needed to keep a 2007-2010 1125R running the way it was built to.