More commonly called a pull start, the recoil starter mechanism causes the engine to sit slightly higher, affecting the center of gravity -- a possible concern in RC racing.
How to Repair your Recoil Starter also explains the parts of a pull start system and how it works. Tamiya provides a several MPEG movies that show how to use a recoil starter.
These videos demonstrate the pull-start or recoil starter method for a nitro RC:

