Abstract: To improve the durability of an air cleaner against water and dirt sucked in from a drain hole. An air cleaner includes an air cleaner element and a case cover. The inside of the air cleaner is partitioned into a clean room and a dirty room by an air cleaner element, and is aligned in a widthwise direction of the vehicle. The dirty room communicates with the atmosphere through an intake hole provided at an upper section, and a drain hole and a drain pipe are provided in a bottom wall section. A rib for supporting a lower end of the air cleaner element is provided above the bottom floor section, and is arranged so as to cross an extension of the axis of the drain pipe. Water and dirt that are sucked into the dirty room through the drainpipe and the drain hole by negative pressure inside the air cleaner have difficulty coming into direct contact with the air cleaner element because of the rib acting as a baffle plate.

Abstract: A compact air cleaner for a motorcycle engine has its intake duct directed in a widthwise direction of the motorcycle. The air cleaner includes an air cleaner case, an air cleaner element and a case cover. The air cleaner element partitions an inner portion of the air cleaner case and case cover into a clean room and a dirty room. The air cleaner element extends in the motorcycle's travel direction. An intake port communicates with the dirty room and opens to a space surrounded by a rear face of the clean room, a front portion of a rear fender and a bottom portion of a seat.

Abstract: A thin U-shaped rear axle guide plate made of steel is detachably attached along rear end portions of rear fork arms made of light alloy and formed in a bifurcate shape. This rear axle guide plate is made longer at its lower branch portion than its upper branch portion, and a free end portion of its lower branch portion includes a projection projecting upward. The rear fork arms are provided at side surfaces opposite to the rear axle guide plate with a retaining pin projecting therefrom. Engaged with this retaining pin is a cam face of a drive chain tension adjusting plate pivotably supported by the rear axle. The adjusting plate is pressed and held by a nut which is in threaded engagement with the retaining pin. The adjusting plate may be formed with an annular rib around an opening in which the rear axle penetrates, and this annular rib may be engaged with step portions formed at the rear fork arms.