TTMRC 4 valve size EX25/IN28 cylinder head.
With this size of valves in head it will be easy for air in and out, and the combustion chamber will work bigger than usually. The upgraded cylinder can increase the efficiency of the intake and exhaust and then get more power.
Can increase power to 25 H.P.
Need use with cylinder 65mm-76mm, long stroke crankshaft +6mm -- +8mm. Also, need to use manifold 32mm 34mm.