Chains are simple and effective, but need regular maintenance. A neglected chain may severely damage the engine case, or wrap up in the wheel and sprocket, locking the rear wheel. The two major types of chain designs are O-ring chains and non-O-ring chains. O-ring chains employ rubber O-rings between their side plates to retain lubricants. These usually last much longer, but although internally lubricated, O-rings need to be kept clean and side plates require lubrication and rust protection.
Scottoiler & Acumen CL10 Electronic Chain Oiler: www.riderstation.com