Echo CS-4920 ChainsawThe CS 4920 features a powerful 50. 1 cc, 2 stroke engine but is the lightest saw in its class. With a purge bulb for easier starts and a momentary switch that returns to the "ON" position when the saw is shut off, the CS 4920 is simple to operate. Features: 50. 1 cc professional grade, 2 stroke engine For outstanding performance and durability Stratifed, 2 stroke engine Results in lower emissions i 30 starting system Reduces starting effort by 30%