The King of the Baggers class presented by MotoAmerica at road race events has been a tremendous success, featuring heavily modified Harley-Davidson Road Glides. These bikes, boasting horsepower numbers in the range of 165 to 185, have impressed many with their ability to achieve fast lap times despite a minimum weight of 620 pounds.
This resurgence in speed reminds Harley riders that while looking cool is fun, going fast can be exhilarating too.
Harley-Davidson now offers its CVO Road Glide ST with the 121 HO engine—121ci (1,977cc) High Output—delivering 127 hp at 4,900 rpm and 145 lb.-ft. of torque at 3,000 rpm. This engine opts for a camshaft with longer, race-inspired valve timing, forgoing the variable valve timing found in non-ST 121 engines, and redlining at 5,900 rpm.
Historically, Harleys have been celebrated for their impressive bottom torque, essential for moving their substantial weight from a standstill. This was achieved with short valve timings, similar to those of a classic VW Beetle. However, as higher-speed travel became more common, performance demands increased, prompting larger engine displacements while retaining strong bottom torque.
Variable valve timing (VVT) has proven useful for acceleration, adjusting the phase angle between cam and crankshaft to optimize valve timing across different rev ranges. However, cam phasers, while able to advance or retard the camshaft, cannot alter valve duration or lift.
Insights from Harley's King of the Baggers (KOTB) racing team have likely influenced the new cam design, which opens the intakes before TDC and closes them after BDC, enhancing cylinder filling and delivering robust bottom-end performance alongside high horsepower.
The KOTB-derived intake Y-manifold, claimed to flow 26 percent more air from the 58mm throttle body, and an updated cylinder head are notable features. Additionally, a new front pulley with 30 teeth, compared to the previous 32, increases rear wheel torque by 6.7 percent.
Higher power outputs mean more heat, highlighting the importance of liquid-cooling around the exhaust valve seats to prevent high-temperature "creep," which can loosen seat inserts or distort valve seats, causing valve leakage and further heating issues. Liquid-cooling ensures critical components remain at safe temperatures, preserving performance and reliability.