A gas-leak-detection device for detecting a gas leakage from an evaporative emission system includes an electric-wire-connection portion and a passage connection portion that are disposed to overlap with at least one of appearance components in a vehicle when the vehicle is seen in a viewing direction, and are disposed closer to the at least one appearance component than a center plane perpendicular to the viewing direction when the vehicle is in an upright state, the center plane being one of an imaginary-lateral-center plane that is an imaginary vertical plane perpendicular to the left-right direction, an imaginary-longitudinal-center plane that is an imaginary vertical plane including a center in the front-rear direction and being perpendicular to the front-rear direction, or an imaginary-vertical-center plane that is an imaginary horizontal plane including a center in the top-bottom direction and being perpendicular to the top-bottom direction.

A gas-leak-detection device for detecting a gas leakage from an evaporative emission system includes an electric-wire-connection portion and a passage connection portion that are disposed to overlap with at least one of appearance components in a vehicle when the vehicle is seen in a viewing direction, and are disposed closer to the at least one appearance component than a center plane perpendicular to the viewing direction when the vehicle is in an upright state, the center plane being one of an imaginary-lateral-center plane that is an imaginary vertical plane perpendicular to the left-right direction, an imaginary-longitudinal-center plane that is an imaginary vertical plane including a center in the front-rear direction and being perpendicular to the front-rear direction, or an imaginary-vertical-center plane that is an imaginary horizontal plane including a center in the top-bottom direction and being perpendicular to the top-bottom direction.

There is provided a straddle type vehicle including: an engine; a fuel tank configured to store fuel to be supplied to the engine; a power generator driven by the engine; a regulator disposed below the fuel tank and configured to adjust electric power supplied from the power generator to a battery; and a regulator cover that includes a side wall covering the regulator on an outer side in a vehicle width direction and an upper wall covering an upper side of the regulator. The upper wall is formed below a side lower edge of the fuel tank to extend from an inner side to the outer side in the vehicle width direction with respect to the side lower edge.

A straddled vehicle engine unit including an internal combustion engine and a misfire detection device. The misfire detection device includes a crankshaft rotation speed fluctuation physical quantity acquisition unit and a misfire determination unit. The misfire determination unit includes first to third determination units. The first determination unit determines whether or not the crankshaft rotation speed fluctuation physical quantity acquired by the crankshaft rotation speed fluctuation physical quantity acquisition unit is greater than a set physical quantity determination reference. The second determination unit determines whether or not a fluctuation pattern constituted by a physical quantity and the crankshaft rotation speed fluctuation physical quantity acquired at least before or after the physical quantity falls within a set misfire pattern range. The third determination unit determines whether a misfire determination is to be set as effective or not, based on results of determination by the first and second determination units.

A cylinder for a V-twin engine includes a section of steel tubing cut to a length. The section of steel tubing includes a first portion having a first wall thickness and a second portion having a second wall thickness less than the first wall thickness. The second wall thickness is less than 0.050 inch. The section of steel tubing includes a first ribbing pattern on an outer surface, within the first portion, and a second ribbing pattern including multiple ribs formed on individual ribs of the first ribbing pattern. A cast body is provided on the first portion of the section of steel tubing so that the section of steel tubing is fixedly secured within the body to form a cylinder sleeve defining a cylinder bore. The second portion having the second wall thickness extends from an end of the body to be received within a bore of a crankcase.

A cylinder for a V-twin engine includes a section of steel tubing cut to a length. The section of steel tubing includes a first portion having a first wall thickness and a second portion having a second wall thickness less than the first wall thickness. The second wall thickness is less than 0.050 inch. The section of steel tubing includes a first ribbing pattern on an outer surface, within the first portion, and a second ribbing pattern including multiple ribs formed on individual ribs of the first ribbing pattern. A cast body is provided on the first portion of the section of steel tubing so that the section of steel tubing is fixedly secured within the body to form a cylinder sleeve defining a cylinder bore. The second portion having the second wall thickness extends from an end of the body to be received within a bore of a crankcase.

An engine unit of a motorcycle includes a crankshaft, a piston, and a swing member. The crankshaft is housed in a crankcase in a direction such that a rotational center line is parallel to a vehicle-width direction. The piston is disposed above the crankshaft and reciprocates in an approximately up-down direction. The swing member is disposed forward of the crankshaft and the piston, coupled to the crankshaft by a coupling member, and swings in an approximately front-rear direction synchronized with a rotation of the crankshaft.

An engine unit of a motorcycle includes a crankshaft, a piston, and a swing member. The crankshaft is housed in a crankcase in a direction such that a rotational center line is parallel to a vehicle-width direction. The piston is disposed above the crankshaft and reciprocates in an approximately up-down direction. The swing member is disposed forward of the crankshaft and the piston, coupled to the crankshaft by a coupling member, and swings in an approximately front-rear direction synchronized with a rotation of the crankshaft.

A two-wheeled vehicle includes a frame having a front frame portion, a mid-frame portion, and a rear frame portion. The mid-frame portion is coupled to the rear frame portion and the front frame portion. The vehicle further includes a plurality of ground-engaging members for supporting the frame. The front frame portion is removably coupled to the mid-frame portion with a plurality of frame members extending between the front frame portion and the mid-frame portion.