"Statistically, it has been found that the average service life of a final drive chain is about 20,000 km, only if it is periodically maintained in accordance with the instructions given in the Owner's Manual of the motorcycle."
Something to add to the general subject of drive chains, briefly alluded to in that excellent
Somewhat obvious, but I have worked on bikes that had this wrong.
Battery acid is immediately fatal to a drive chain.
Battery vent tube outlet should be routed to the opposite side of the bike.
A dramatic demonstration is to hang an old used up chain, and brush some acid on it.
You'll hear a crackling sound as the links fracture and often the result is chain pieces
in a pile on the floor.
I discovered this as a kid when I put Naval Jelly rust remover on my bicycle chain.