When the hot-button thread of lubing vs. not lubing a chain surfaces in motorcycle discussion groups, the use of WD40 always enters the fray.
Often tons of anecdotal “proof” championing WD40 as a sole lubricant follow, unhampered by scientific controls for riding style/conditions, usually involving some pretty stout mileage figures. Read everything and decide; it’s your $200 chain/sprocket set.
WD40 is not a motorcycle chain lube
Since the “WD” part of the name supposedly means “water displacer,” I use this product (actually, a generic equivalent available at generic discount stores at a generic price) after washing my motorcycle or a ride in the rain. Liberally sprayed on the wet motorcycle chain links, it seems to replace the water, reducing the potential for rust to form.
Rather than stopping there, I wipe the chain dry (do NOT do this with the engine running unless you were born with surplus fingers!) and apply a proper chain lube. PJ1 Black and DuPont Teflon Multi-Use Lubricant are my two favorite sprays — shake well to mix the carrier with the actual lube.
Why not just stop after WD40?
It would be better than absolutely nothing, but WD40 is said to be mostly kerosene. I don’t think it lasts more than around the block. If you’re performing this maintenance prior to parking the bike, it will have evaporated before your next ride.