Abstract: A riding simulation system of motorcycle provides at least a model motorcycle on which a person can ride and which can be operated by a person. In response to the operation and movement of the person who rides on the model motorcycle, the model motorcycle is moved by a movable mechanism in a desirable direction such as a yawing direction, a rolling direction and a pitching direction. Preferably, the moving image such as the scenery which is seen from the running motorcycle is displayed in front of the person who rides on the model motorcycle. Such moving image is varied in response to the driving condition of the model motorcycle.

Abstract: Method and apparatus for adjusting tension on a timing belt of an engine. The engine includes a driving pulley on its crankshaft, a driven pulley on its camshaft, an auxiliary pulley, a timing belt bridging over the pulleys and a tension pulley pressing against the belt at one side. The driving pulley is first reversely rotated while the driven pulley is held fixed in position thereby tensioning the portion of the belt between the auxiliary pulley and the driven pulley. The driving pulley is then rotated normally to overtension the tension side portion of the belt while the tension pulley is advanced to take up any slack. Thereafter, the tension pulley is retracted while the driving pulley is reversely rotated until deflection of the tension side portion of the belt reaches a predetermined target adjustment value. The tension pulley is then fixed in position.