Worst, a 79 rm125. Even look at a trail, and it would overheat. I spent most of my time waiting for it to cool down so I could go for another 5 minutes. Best, my 2000 DRZ 400. Absolutely bulletproof with a nice,wide useable power band. Once I had the suspension revalved, it was simply amazing on almost every thing. 04' yzf 450, time will tell, but so far I'm in love with this bike.