you can see 2hp depending on which tire was used on the dyno with these small motors

porting needs puddy more than grinding IMO, cam could really be improved on too

the cam uses really slow velocitys which lifts and sets the valave back down on the seat easily, designed for durability. The timing at 1mm lift basically has the it running with no overlap so there is no real scavenge effect from the pipe. The intake acts restricted because as the intake valve chases the piston down it's not getting out of the way of the incomeing charge fast enough, bigger valves may help a bit, but better cam timing and velocity and lift would help a whole lot more.