A work apparatus has an internal combustion engine. The internal combustion engine includes a crankcase in which a crankshaft is mounted rotatably about an axis of rotation. The work apparatus includes a fan spiral and a fan wheel arranged in the fan spiral for conveying cooling air for the internal combustion engine. A cylinder is arranged on the crankcase, and the cylinder includes a first outer side facing the fan wheel and a second outer side facing away from the fan wheel. The fan spiral has a first outlet opening for a first cooling air flow for cooling the first outer side of the cylinder. The fan spiral has a second outlet opening for a second cooling air flow for cooling the second outer side of the cylinder.

The intake structure for an internal combustion engine includes: a collision surface configured to face an inlet of a carburetor; a deflecting surface configured to deflect a blowback flow, which is to diffuse after colliding against the collision surface, in one direction along the collision surface; a receiving surface configured to receive the blowback flow deflected by the deflecting surface; and a fuel-accumulating surface formed below the collision surface. A first clearance between an air-guiding direction distal end of the deflecting surface and the receiving surface is brought into communication to a downstream side of a filter of an air cleaner in a fresh-air intake direction so as to act as a main intake passage for fresh air.

An engine includes a breather conduit, an intake conduit, and an air filter assembly. The assembly includes a filter element having a top wall, a bottom wall, a first aperture through the bottom wall, a second aperture through the bottom wall, and filter media extending between the top and bottom walls, wherein the first and second apertures are the same shape, the same size, and are equally spaced apart from the center of the bottom wall. The filter assembly also includes a case. The filter element is configured to be received in the case such that the breather conduit and the intake conduit are directed to and from the interior chamber of the filter element, respectively, whereby air filtered by the filter media mixes with unfiltered gases from the breather conduit in the interior chamber of the filter element prior to entering the intake conduit.

Handheld construction equipment may include a crankcase scavenged combustion engine arranged to drive a work tool where a fuel injector is configured to provide a controlled amount of fuel into an air and fuel intake flow of the combustion engine, and where an idling air flow channel is arranged to connect with the air and fuel intake flow of the combustion engine in connection to the fuel injector.

A simple engine, comprises (1) a cylinder and a spark plug in the cylinder; (2) a carburetor, fluidly connected to the cylinder; (3) a primary air intake path, fluidly connecting atmosphere to the carburetor; (4) a carburetor bypass air intake path, fluidly connecting air to the cylinder without passing through the carburetor; and (5) a valve, along the carburetor bypass air intake path, for controlling the flow of air through the carburetor bypass air intake path.