An engine for an offroad vehicle including a crankcase, a transversely extending crankshaft, and a transmission connected to the crankshaft. The transmission includes a drive pulley, a driven pulley, and a drive belt connecting the drive pulley and the driven pulley. The driven pulley includes a fixed half and a movable half. A spring is adapted to bias the movable half toward the fixed half. A transmission primary shaft is connected to the drive pulley and is coaxial to the crankshaft. A transmission main shaft is connected to the driven pulley. A transmission case is connected to the crankcase. The crankcase includes a cavity and the transmission case includes an opening that corresponds with the cavity such that the main shaft extends through the cavity and the opening. The spring is at least partially positioned within the cavity.