Tillotson 196cc Clone Reinforced Big Bore Block - 72mm - Modified/Open ClassPushing the absolute limits of 196cc clone engines demands high caliber racing parts that won't fracture under extreme cylinder pressures. The Tillotson 72mm Reinforced Big Bore Block is engineered specifically to handle the intense thermal and mechanical stress of high RPM competitive karting. By providing the critical displacement needed for that extra burst of speed on tight tracks, this block prevents the catastrophic mid race failures common with