Patent ID: 7343998

Claim:
An all-terrain vehicle comprising: a frame; a straddle seat mounted on the frame for supporting a driver; at least four wheels suspended from the frame, the at least four wheels including a front pair of wheels defining a front wheel axis and a rear pair of wheels defining a rear wheel axis, each wheel being disposed with a low-pressure balloon tire; and an engine mounted to the frame, the engine comprising: at least one cylinder unit, the at least one cylinder unit including a cylinder and a cylinder head, the cylinder having a cylinder bore and a cylinder bore axis; and a piston, the piston being disposed in the cylinder bore in order to reciprocate along the cylinder bore axis, the cylinder being slanted such that the cylinder bore axis is inclined with reference to a vertical axis, the engine powering a crankshaft in driving engagement with a transmission, the crankshaft being supported in the engine casing to rotate about a crankshaft axis, the transmission being in driving engagement with a subtransmission, the subtransmission being contained within a subtransmission casing, the subtransmission having an input shaft operatively connected to the crankshaft, the input shaft being supported in the subtransmission to rotate about a subtransmission shaft axis, the subtransmission shaft axis and the crankshaft axis defining a first reference plane, a first reference angle defined between the cylinder bore axis and the first reference plane being between 85° and 5°, the subtransmission including reduction gearing for driving a rear drive shaft operatively connected to a rear differential for delivering torque to the rear wheels, wherein the subtransmission casing is detachably mounted to the engine casing and secured thereto by at least one threaded fastener.