QR Code Link to This Post Freshly rebuilt CBR300R engine. New crank, crank bearings, clutch, piston/rings, cylinder, valves, valve job, and more. Assembled by a former CBR250R/CBR300R roadrace champion. Slot this into your CBR, CRF, or Grom! Engine has been started and broken in. Shows 225 PSI compression and 4% leakdown at 60 PSI. Very healthy!