The YZ60, KX60, and CR60 all made about the same hp. The KX60 had the most sophisticated suspension and beefiest frame, so all the parents started buying those. Honda and Yamaha stopped selling 60s here around the same...the YZ60 was the bike to have in 81-82, as the RM60 sucked (twin shocks! 4" of suspension travel)...but the YZ60 lacked a linkage monoshock (had the old style one), and had less travel front and back the CR60 and KX60. I had an 83 YZ60 and it was very strong in the midrange.