Abstract: An internal combustion engine (1) includes a supplemental fuel passage (26, 27) which connects the carburetor (9) to the exhaust chest cover (28). A supplemental air inlet having a metering orifice (36) and passage (35) connects to the supplemental fuel passage. The resultant air-fuel mixture is heated before entry into the combustion chamber by passing the mixture through a heating passage (32) directly in front of the exhaust ports (13). When the engine is at idle with a completely closed throttle valve (19), the entire air-fuel supply for the engine is provided through the supplemental fuel and air passages and is heated in the heating passage prior to combustion. At increasingly open throttle, air-fuel is increasingly provided from the conventional primary carburetor output, with the heated air-fuel mixture being supplied in gradually decreasing amounts.

Abstract: Improved throttle and spark advance linkage is suitable for use in a marine drive, such as an outboard motor, having a throttle valve, a throttle operator with a cam follower for opening and closing the throttle valve, means for altering the ignition timing, and maximum and minimum spark advance stops. The linkage includes a spark advance lever pivotally mounted on the marine drive. The spark advance lever is coupled to the means for altering the ignition timing so that the timing is advanced and retarded responsive to the pivotal movement of the spark advance lever. The spark advance lever has means engaging the maximum and minimum spark advance stops for limiting the pivotal movement of the spark advance lever. A throttle lever is pivotally mounted on the marine drive coaxially with the spark advance lever. The spark advance lever and throttle lever have cams coacting with the cam follower on the throttle operator for opening and closing the throttle responsive to pivotal movement of the levers.

Abstract: A two cycle internal combustion engine (10) has at least two cylinders (12, 13) which fire alternately with pressure in one crankcase (17 or 18) at the time there is vacuum in the other. Supplemental fuel flow passages (36, 41) extend from each crankcase and are joined at a common passage (46) connected to the float bowl (30) of the carburetor (20). A normally closed control valve (48) is disposed in the common passage. When the engine is to be started, the control valve is opened so that fuel enters the supplemental and common passage. Initial rotation of the crankshaft (16) causes pressure in one crankcase to force fuel toward the other crankcase, which has vacuum. Further crankshaft rotation reverses the pressures so that fuel is then forced toward the opposite crankcase. Continued engine operation with the control valve open causes alternate fuel flow reversals together with pressurized alternate fuel injections into the respective crankcases, which are independent of the throttle setting.

Abstract: This invention comprehends a two-cycle internal combustion engine using compression relief to provide a dual compression ratio. Compression relief ports above the exhaust ports of two cylinders firing 180 degrees out of phase connected by a relief passage. The passage is vented at its midpoint. At higher engine speeds exhaust flow, from the cylinder in its power stroke, through the relief passage, blocks the flow from the cylinder in its compression stroke.