The invention discloses a novel cam shaft. The novel cam shaft comprises a cam shaft, a chain wheel and a holder, wherein the chain wheel is fixed with one end of the cam shaft through the holder, a first screw hole and scales are arranged on the chain wheel, an arc-shaped through hole is formed in the part, corresponding to the first screw hole, of the holder, an indication part is arranged at the part, corresponding to the scales, of the holder, and the screw penetrates through the arc-shaped through hole and is connected with the first screw hole. The arrangement of the scales is increased on the cam shaft, the relative position of the cam shaft to the chain wheel is regulated through matching the scales with the indication part, the regulating range of the time sequence difference between a piston and a valve is increased to realize a fine adjustment effect, and at the same time, the regulating process is simplified.