Silicon carbide (SiC) is known for its outstanding mechanical properties, which is widely studied in the microelectromechanical systems (MEMS). Recently, the mechanical tuning of defect centers in 4H-SiC has been demonstrated, which enables its application in quantum spintronics. This work reports a lateral overtone mechanical resonator fabricated from a semi-insulting (SI) bulk 4H-SiC wafer without epitaxial layers. The resonator shows a series of modes with quality factors (Q) above 3000. A mechanical tuning effect on the quality factor is found on the overtone device, showing a 22% improvement in the Q at the targeted 300 MHz frequency and suppression on the overtone modes away from it. This device also allows optical access into the SiC defects from both sides of the wafer, which can be used in quantum applications.