Last weekend I put the 13T 140L sprocket
on my wifes KLX 140. The smaller front sprocket helped, but not nearly as much as I thought it would. Her last bike was a 2001 XR 100. I'm not sure if it had stock sized sprockets or not. I never really looked as it was her first bike, and we had little experience at the time. I will assume it was stock as everything else on the bike was stock. Seems even with the 13T in the front and stock 50T in the back of her 140, it has no where near the low end power of the '01 XR. When she'd stall out on a nasty hill climb on the XR, I could jump right on it in the middle of the climb, and it would tractor me right up anything. I'm about 6'4", 200 lbs so I was impressed with the XR climbing power. Even with the 13T in the front, when we went out to the hills yesterday, if I ever stopped the bike on any decent climb, it still didn't have the power to even get the back wheel spinning again with me on it. I'm thinking of putting a 54T rear sprocket on (this would be a KX80 428 conversion sprocket) and seeing if that fixes the problem. Does anyone else have any input on this issue? Is there something I don't know about that makes the XR a better trail / climbing bike than the KLX 140?