Below is Ari's, from Motorcyclist MC Garage, take on the subject that I'm sure you'll enjoy. His video is not the definitive answer on using WD40 on a motorcycle drive chain but some will like it. He agrees with using WD40 for cleaning but not lubricating a motorcycle chain. To me this subject parallels the question "What oil should I use in my motorcycle?" You can get hundreds of different answers. Depending on the way the wind is blowing the day this question is asked then answered may or may not match one's own idea of just what oil should be used. 😂
Yep, I agree with everything he said......except you don't need to lube an O ring chain (again, not to sound like a broken record, but Bill's testing proved that beyond any reasonable doubt IMO). That said, I believe that you may be able to extend the life of your chain and sprockets by using a good chain lube......but it's just not worth the mess for me and the cost of a chain and sprocket set every few years isn't a big deal for my usage.... Bill even opined that the savings in chain lube would likely pay for a new chain and sprockets ;-) If I commuted 50 miles a day on my KLR's, I may be more inclined to try to optimize the life of those components. This all reminds me of the Scott Oiler that resides in my spare parts bin.....what a mess maker that thing was!
I don't think the "to use or not use a chain lube on an O ring chain" question really has a right answer. The one FACT out of all this is that WD40 will not harm your chain or O rings.