In SR engine, in the situation that engine keep rotates over 7000rpm while circuit run or drag racing, or over-rev from miss shifting will sometimes leads tappet side of the rocker arm fulcrum to jump, and rocker arm to come off. Locker arm stopper is the parts which holds the lash adjuster side of locker arm with fixed clearance, controls the deflection of locker arm when jumping occurred, and protects engine from damage.