why are you not using allen head screws in the engine, much much better than the stock stupid philips heads, can be torqued more easily too.
anyways - a point in the discussion - the reason why this bike accelerates harder than a kawasaki GTO125 is because it torques like a diesel in the midrange (boost port and YEIS bottle capturing the backwash) and starts to scream at the top end due to the reed valve design as compared to the rotary valve in the kawasaki.
BUT - I had built a Kawasaki a very very long time ago - it raced only once and crashed - it raced against a Honda Civic VTI at that time and beat the **** out of it on acceleration,,
In a rotary valve engine you have only one end of the game, mid rpm OR high rpm not both.. I reshaped the intake port and carefully rebuilt the inlet tract aiming it towards the piston skirt; clearanced the disc valve to 0.2mm, redid the piston skirt and put really heavy springs on the clutch basket - and remade the exhaust shell for a proper expansion chamber and a stinger on the end..
But a stinger setup on an RX with proper tuned expansion and reeds will make it scream like a mad banshee