Here is one big difference between motorcycle chains and bicycle chains: Motorcycle chains have bushing that are press fit between the inner chain plates. The pins, press fit to the outer plates, ride in these bushings. Bicycle chains don't have separate bushing and instead, the inner plates are formed to create bushings. The formed bushings on opposing inner plates meet but are not joined in the center of the chain. Lube placed on the roller of a bicycle chain can wick down under the roller, through the gap between the side plate bushings and onto the pin. In motorcycle chains, there is no such path. To lube the pin, the lube has to go between the inner and outer side plates. As others have pointed out, most motorcycle chains have rubber seals around the pins between the inner and outer plates to keep the factory lube in, but they also keep any subsequently applied lube out. When you lube a motorcycle chain, you're basically only lubricating the rollers and keeping the outside surfaces of the chain from rusting.