I switched to an o-ring chain and had to order a replacement chainguide because the chain is thicher. FRP has a nice one. I think it will also fix your problem, he is very informative give him a call. http://justkdx.dirtrider.net/newfredlist.html
it may be a bit late for this now but you can also go to a 12 tooth countersproket and get the same effect and not have to buy a new chain, its a sweet deal makes the bike rip of the bottom a bit faster and makes 2nd and 3rd gears much more usable without sacraficing much on the topend. i recomend this mod no matter where you ride in tight areas or wide open.:cool:
I agree, the FREDETTE RACING chain guide is the way to go. I bout one for my OLD 92 KDX, and then just TRANSFERED it over to my 97. Only replaced the plastics in the guide twice so far. That thing is BULLETPROOF! I ride TOATALLY IN ROCKS also.
I seem to find the 13/49 tooth combination works pretty well for me. Im 6', and 180lbs. I find myself riding in 3rd gear mainly, and that leaves the powerband right at my fingertips.