Abstract: A snow vehicle of the saddle-riding type utilizes essentially the same upper structure as a motorcycle but mounts a ski on the front fork for steering and an engine-driven endless belt track assembly for powering the device. The endless belt track assembly is arranged for mounting on a rear arm structure in order to maintain surface contact between the endless belt and the snow and thereby improve the operating efficiency of the vehicle. The arm may be pivotally mounted or integral with a rear fork pivotally mounted to the vehicle. An improved endless belt construction is described in which the belt is strengthened by core members and the driving cogs of particular configuration and disposed at prescribed locations with respect to the propelling lugs in order to maintain surface contact between the belt edge and the snow surface during cornering. Also disclosed are various forms of cover structures for the track assembly that prevent the scattering of snow from the belt onto the rider or vehicle parts.

Abstract: An engine controller is linked to and controls simultaneously both an exhaust control valve and an on-off valves or changeover valves or a reflector in the exhaust pipe to improve engine performance. The controller positions the exhaust control valve and on-off valves or changeover valves, or reflector based upon detected engine speed and throttle position.

Abstract: An exhaust timing control apparatus for two-cycle engines of the type having one or more exhaust ports extending outwardly from the cylinder. A valve body is pivotally mounted within the exhaust passage in a recess specifically provided therefore. The valve has a control surface approaching the cylinder to define an apparent upper timing edge of the exhaust port. Holes are provided through the valve body for flow to operate to inhibit the build up of carbon deposits which often inhibit the operation of the valve. An inclined surface may be formed on the surface of the valve body to facilitate the removal of carbon. Edges may also be provided on the valve body which cooperate with the walls of the recess in the exhaust passage to knock off carbon build up such that it might be conveyed through the exhaust pipe and from the system.

Abstract: An exhaust timing controller for controlling an exhaust timing member in a two cycle engine including a control circuit for generating a control signal which actuates a mechanism for moving the exhaust timing member. The control circuit controls the member such that the member is drivable in a range from a fully open position to a fully closed position responsive to certain engine conditions including engine speed and rate of change of engine speed. A self cleaning cycle is provided which drives the exhaust timing member first to one position limit and then to the other.

Abstract: A two-cycle engine includes a cylinder block having at least one pair of first and second cylinders, the first and second cylinders having a pair of first and second exhaust ports, respectively. A pair of first and second pistons are received respectively in the first and second cylinders for reciprocal movement therealong, each of the exhaust ports being selectively closed and opened by a respective one of the pistons during the movement thereof along a respective one of the cylinders. The first and second pistons are operatively connected to a crankshaft in such a manner that the first and second pistons are reciprocable 180.degree. out of phase along the respective cylinders. A final portion of the duration of opening of one of the exhaust ports overlaps an initial portion of the duration of opening of the other. An exhaust passage has a communicating portion communicating the first and second exhaust ports with each other adjacent thereto.

Abstract: An exhaust system control apparatus for the exhaust of an internal combustion engine which is particularly useful on two-cycle engines. The exhaust system includes a subsidiary chamber connected to the normal engine exhaust passage with a valve for opening and closing communication between the chamber and exhaust passage to change the pressure wave at the engine cylinder exhaust port to provide optimum performance at high and low speeds. The chamber valve is operated rapidly by a pneumatic actuator supplied with compressed air from one or more of the sources disclosed, namely, a belt driven or electric air compressor and piston and cylinder devices extending between or forming the suspension components of a two wheeled vehicle. A pneumatic valve is operated by engine speed sensing means to supply or release the pressurized air to the actuator at a predetermined engine speed.