Dont worry have a look at this :
Limited engine speeds or RPM: OHV engines have more valvetrain moving parts, thus more valvetrain inertia and mass, as a result they suffer more easily from valve "float", and may exhibit a tendency for the pushrods, if improperly designed, to flex or snap at high engine speeds. Therefore, OHV engine designs cannot revolve ("rev") at engine speeds as high as OHC[SUP][/SUP] Modern OHV engines are usually limited to about 6,000 to 8,000 revolutions per minute (rpm) in production cars, and 9,000 rpm to 10,500 rpm in racing applications
Overhead valve - Wikipedia, the free encyclopedia
It is common to every pushrod engine (CG, Paiggo, Harlay any pushrodder) if you redline it above its working capacity it will lose power because of 'Floating Valve' ...