I have been looking around at backpack leaf blowers, but I do not know what the difference between two-cycle and four-cycle engines is. Can anybody explain?
Two-cycle engines require a mixture of gas and oil in the tank, and are lighter weight and simpler to maintain than four-cycle engines. Four-cycle engines are more fuel efficient and can produce more power, but are usually heavier than two-cycle engines.
Here is a link that might be useful: Backpack Leaf Blower Buyer's Guide