Harley's engineering staff made many mods to bring the Sportster's venerable air-cooled, pushrod V-twin up to XR spec. A larger crankpin (1.5 inches, compared to the standard XL1200's 1.25 in.) fitted with a racing-quality roller bearing beefs up the bottom end, and a higher-flow oil pump is now driven off the cam to reduce "social noise." Bore and stroke remain unchanged at 88.9 x 96.8 mm, as does valve train geometry and valve diameters, but a new cam similar to that of the Buell XB provides a power boost. Redline has been increased 1000 revs to 7000 rpm and compression rises from 9.7:1 to 10:1. Oil-cooled cylinder heads appear for the first time to better control temperature (especially exhaust-valve temps), with a small oil cooler mounted to the frame downtube. A Delphi-made ECU controls the sequential-port fuel injection that features a larger, 50mm Dell'Orto twin-throat throttle body (up from the XL's 45mm). The intake has been reconfigured to a downdraft arrangement, compared to the sidedraft format of the standard Sportster, and the traditional side-mounted air cleaner has been replaced by an under-tank airbox. H-D's Active Intake System makes an appearance here, utilizing a solenoid-activated flapper to cancel resonance at certain rpm to reduce noise. The five-speed transmission is unchanged, though the primary drive ratio has been raised from 1.50 to 1.68 for snappier acceleration.