S&S 551 Easy Start Cam Kit For Harley Twin Cam Features: Start any engine regardless of displacement or compression ratio with a stock starter The new Easy Start Cams from S&S Cycle make hard starting obsolete Here's how it works: Each of the two exhaust cam lobes are equipped with a spring loaded compression release lobe on the heal of the cam at the point where the valve would normally be fully closed, the lobe holds the exhaust valve open slightly at cranking speed, this releases some of the compression, making the engine much easier to crank , once the engine starts, and rpm increases, the compression release lobe is centrifugally retracted and the engine runs normally, with full compression, and without any loss in performance Allows a stock starter and battery to start nearly any engine Don't get caught dead without them! Centerline Intake: 92.5 Duration Exhaust .020: 237 Grind: 551C Lift Top Dead Center Intake: .163 Duration Intake .020: 215 Lift Top Dead Center Exhaust: .179 Lift: .550 Valve Timing Exhaust: 39/18 Centerline Exhaust: 100.5 Valve Timing Intake: 15/20