Yamaha R15 V4

"The sharpest 155cc you can buy used, full stop."

The R15 V4 is genuinely impressive for what it costs used, and I say that as someone who's thrown a leg over everything from CBR600s to Panigales. The VVA engine is legitimately clever — that variable valve system makes it tractable at low revs without killing top-end excitement. Slipper clutch, USD forks, traction control on a 155cc bike? Yamaha weren't messing around. Ergonomics are aggressive though, and I mean properly aggressive. Taller riders above 5'10" will be folded like origami on longer runs. When buying used, inspect the fairings obsessively — these attract new riders who drop them in car parks more than they'd admit. Check the VVA solenoid is functioning smoothly across the rev range; a hesitation around 7,500rpm is the telltale sign of trouble. Service history matters here because neglected oil changes kill the top end early. Most examples you'll find have been commuter-thrashed, so look for chain wear and front fork seal leaks religiously.