Abstract: To effectively reduce noise caused by an attachment part of a cam chain guide without increasing a pressing force of a cam chain tensioner more than is necessary. A cam chain guide for slidably guiding a cam chain at a valve gear of a four cycle engine is made of resin. An attachment hole for an attachment bolt is provided at an attachment end section for the crankcase. Side surface projections are provided equally spaced at the periphery of an attachment surface surrounding the attachment hole so as to project from a normal surface. Annular recesses are formed at the peripheries of each of the side surface projections. Furthermore, inner surface projections are provided at the inner peripheral surface of the attachment hole equally spaced about the periphery so as to project in a central direction.

Abstract: A rubber composition suitable for reinforcing beads of tires, having high hardness, high durability and high aging resistance, which comprises a rubber component containing 30 to 70% by weight of a butadiene rubber containing syndiotactic crystals, 60 to 75 parts by weight of a carbon black having a specified iodine adsorption number and a specified oil absorption, 1 to 2 parts by weight of sulfur and 2 to 4 parts by weight of a sulfenamide accelerator, respectively, per 100 parts by weight of the rubber component, wherein the total amount of sulfur and the sulfenamide accelerator is from 3 to 5 parts by weight.