Abstract: An oxygen sensor element 1 includes: a cup-shaped solid electrolyte body 10, inside of which a reference gas chamber 13 is provided; a measuring electrode 11 that comes into contact with measured gas; and a reference electrode 12. A heater 2 is disposed inside the reference gas chamber 13. The measuring electrode 11 is formed surrounding the outer surface 101 in a tip end section 100 of the solid electrolyte body 10. The reference electrode 12 is formed in a measuring-electrode-opposing-region 102a that is a region on the inner surface 102 of the solid electrolyte body 10 opposing the measuring electrode 11 with the solid electrolyte body 10 therebetween. The area S1 of the measuring electrode 11 and the area S2 of the reference electrode 12 satisfy a relationship 0.010?S2/S1<0.723.

Abstract: In a motorcycle, an increase in the wedge effect of the upper cowl occurs with respect to the wind buffeted thereto during travel for reducing wind drag while maintaining continuity of the upper surface of the screen with respect to the upper surface of the head of the rider in a fully bent posture while providing a meter with high visibility even for the rider in a fully bent posture. In a motorcycle wherein the upper surface of the upper cowl covers the upper end portion of the front fork and is formed into a convex surface with a backward rising gradient a screen is provided having an upper surface formed into a convex shape with a backward rising gradient mounted on the upper cowl around the periphery of an open-rear notch for mounting the screen. A meter is disposed inside the upper cowl and the screen.