I've not seen anything about it with the KLX, but the Yamaha WR riders are having issues where the chain can wear through the slider and actually cut the alloy swing arm through. There is a thread on it at the ADVrider forum. Can it happen on the KLX? I don't know, but I don't plan to find out. The smaller counter shaft sprockets can cause that wear, larger ones will keep the chain further away from the swing arm or at least lighter on the slider and on it less often.

I will eventually go 15T as the general size, making the gearing what I will want by using a larger rear sprocket, only go to a 14T to gear down for lower off road riding, and only in extreme circumstances go to a 13T rather than the one always used. It just makes mechanical sense. Sure it costs more for the rear sprocket, but in the long run it will reduce wear on the slider and also on the sprockets and chain. Definitely a thing to do if buying new chain and sprockets front/rear.

Riders can do as they please, but there are the points for staying with the larger sprocket sizes.

 

Mark,
A number of years ago, there was one member here who showed a rather chain-worn swingarm. Doesn't seem to occur frequently. Keep an eye on that slider.

 

So I guess it can happen. Those WRs are actually cutting deep enough to open a hole into the pivot bolt tube. If I could get with a WR rider I'd love to see if I could come up with a metal plate to fit under the slider where the chain can hit first, without cutting through. Problem is no WR swing arm to work with.

 

 

I also want to add that my top speed increased. Before the new chain and sprocket, top speed for me was 84mph with removed snorkel and head tucked down. Post chain and sprocket, I hit 90 with my head tucked. I felt I could have gone a bit faster but hott demn those winds are intimidating.