An exhaust valve assembly for a two-stroke internal combustion engine has a valve actuator, and a two-part valve having a primary and secondary valves defining first and second decompression passages respectively. The primary valve is operatively connected to the valve actuator. The primary valve is in first, second and third primary valve positions when the valve actuator is in first, second and third actuator positions respectively. The secondary valve is in a first secondary valve position when the valve actuator is in the first or the second actuator position and in a second secondary valve position when the valve actuator is in the third actuator position. The first and second valve decompression passages fluidly communicate with each other when the valve actuator is in the second actuator position, and are fluidly separate from each other when the valve actuator is the first or the third actuator position.

An exhaust valve assembly for a two-stroke internal combustion engine has a valve actuator, and a two-part valve having a primary and secondary valves defining first and second decompression passages respectively. The primary valve is operatively connected to the valve actuator. The primary valve is in first, second and third primary valve positions when the valve actuator is in first, second and third actuator positions respectively. The secondary valve is in a first secondary valve position when the valve actuator is in the first or the second actuator position and in a second secondary valve position when the valve actuator is in the third actuator position. The first and second valve decompression passages fluidly communicate with each other when the valve actuator is in the second actuator position, and are fluidly separate from each other when the valve actuator is the first or the third actuator position.

An intake cam is positioned between first and second shaft supports that support an intake camshaft. An exhaust cam is positioned between third and fourth shaft supports that support an exhaust camshaft. An ignition plug unit extends between the intake camshaft and the exhaust camshaft and inward of the intake cam and the exhaust cam with a cylinder axis defining a reference position. A cylinder head includes a joint plane that is joined to a cylinder body. In a case where a virtual plane is defined by the joint plane and is perpendicular or substantially perpendicular to the cylinder axis, a distance between a portion, closest to the virtual plane, of the intake camshaft and the virtual plane is less than a distance between a portion, farthest from the virtual plane, of the intake port and the virtual plane.

An engine is described having a crankcase, a liner and a head assembly. The crankcase is split along a plane defining a two part crankcase, where fluid passages are passing through only one of the crankcase portions, so as to not require crossing the split line. A connecting rod also includes a tapered end, and the piston has a complementary carrier receiving the connecting rod.

An engine is described having a crankcase, a liner and a head assembly. The crankcase is split along a plane defining a two part crankcase, where fluid passages are passing through only one of the crankcase portions, so as to not require crossing the split line. A connecting rod also includes a tapered end, and the piston has a complementary carrier receiving the connecting rod.

An internal combustion engine includes a cylinder head, a crankshaft, intake and exhaust camshafts, first and second chain covers, a chain, and a fastening bolt. The first chain cover having a cutout includes a first flange positioned at a specific edge portion of the cutout, which is positioned between the crankshaft and the camshafts, and a first boss through which a shaft portion of the fastening bolt is passed. The cylinder head includes a second flange, and a second boss into which the shaft portion is inserted, and which is disposed coaxially with the first boss. The liquid gasket is held between the second flange and the first flange. A groove is provided in at least one of a position between the first flange and the first boss of the first chain cover and a position between the second flange and the second boss of the cylinder head.

A product for applying tension is disclosed. A block may have a first passage opening into the block. A body may have a first manifold and may be positioned against the block so that the first passage is open to the first manifold. The body may have a flow path for providing fluid from the first manifold to a second manifold and there through to a pressure chamber. The flow path may include a series of channels and may be configured to allow substantially unimpeded flow from the first manifold to the second manifold, and to impede flow from the second manifold to the first manifold. The flow path may be free of movable components.

The overhead camshaft engine (10) includes a cylinder block (11), a crankcase (12) attached to a lower part of the cylinder block to define a crankcase chamber (32), a bearing retaining member (60) attached to a part of the cylinder block, a crankshaft (20) rotatably supported by a pair of bearings (21, 22) supported by the cylinder block and the bearing retaining member, respectively, and a crankshaft pulley (53) attached to a part of the end of the crankshaft projecting outward from the bearing supported by the bearing retaining member.

In an overhead cam engine (10) having a first bearing (21) supported by the cylinder block (11), and a second bearing (22) supported by a bearing retaining member (60) attached to the cylinder block inside a crankcase chamber (12) for rotatably supporting a crankshaft (20), the crankshaft is provided with a reduced diameter portion (24b) having a smaller outer diameter than an adjoining part of the crankshaft on a side of the second bearing facing away from a cylinder (15) defined in the cylinder block, and a crankshaft pulley (53) is mounted on the reduced diameter portion.

A valvetrain conversion kit for an engine can comprises at least one timing idler rim gear configured to be meshed with at least one of a crank gear of the engine and a cam gear of the engine. The kit can include a first timing gear chamber member having a plurality of engine mounting locations corresponding to a plurality of corresponding cover mounting locations on an internal combustion engine body. The first timing gear chamber member can be configured to be rigidly attached to an engine body at the plurality of engine mounting locations. The first timing gear chamber member can also include a timing idler rim gear shaft supported by the interior surface, the timing idler rim gear shaft having an exterior shaft surface where the exterior shaft surface is configured for rotatably supporting the timing idler rim gear.