I have a 04 cr125r stroked 2mm and 2mm overbore, I didn,t want the 2mm overbore. Anyway the engine builder calls it a 144, it might be a 151. I know that,s strange, that he calls it a 144 and a 151. It hits harder than a mod. cr500 hill climb bike, 21 ft. lbs. of torque, quicker than you can blink. There is no build up of power, you touch the clutch and shazam sam, it,s like your hooked up to a transformer, very fun. The 1st plating was done wrong, replated and welded the exhaust port bridge, the exhaust port bridge broke again. I shipped it to a different plater,and I,m waiting on the cylinder now. Honda,s have a thin exhaust bridge, and breaking the bridge is common.