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Originally Posted by Highside  Your the man if you can improve on that piston. .035 from deck. valves .050 and .045 from piston. 13:1 The valves take up 75 percent of the chamber so sinking them would really hurt compression. Unshrouding, yes. But there goes quite a bit of compression. This motor should not be compared to the norm though. I haven't fully figured it out myself, I have flow numbers saying that the engine should make almost 30 hp but it doesn't. HP per cc this thing stomps 450s though. |
You can go .023 piston to head. And as for the flow numbers, Try welding up the floors and shrinking up the ports. Intake is wrong shape, and the exhaust is just plain to big. You can make a CRF150R make 30hp pretty easily if ya mod it enough and the right fuel.
I build alot of RoadRace bikes and most ports are too big. ( except most the of the Kawi's ) You reduce the exhaust on a Yamaha R6 and you'll pick up almost 5 hp alone doing the intake to will net you another 5. I do it all the time.
And as far as the piston you are showing, It's nice but make it 3 mm bigger in bore, do some mods and measure your compression.
