| 摘要 |
PURPOSE:To facilitate the through-working as well as improve the accuracy of port timing by a method wherein one exhaust port is made larger in port diameter than the other, and is arranged in a biased position above the other port in the titled body equipped with a plurality pair of scavenging and exhaust ports within the cylinder. CONSTITUTION:The cylinder block consists of a block main body 10 and a sleeve 20 fixed within an inner bore 11. A recess 12 forming a part of scavenging passage is provided at the lower end of the block main body 10, at the side of which a recess 13 forming a part of exhaust passage is also provided. Three pairs of scavenging and exhaust ports are formed at the block main body 10 and the sleeve 20 by through-working from the side of the recess 13. Thereby, the respective exhaust ports 21b-23b formed in the sleeve 20 are faced respectively to the scavenging ports 21a-23a, as well as the central exhaust port 22b is made larger in port diameter than the other, and is arranged in a biased position above the remaining two exhaust ports 21b and 23b arranged at the both sides of the central exhaust port 22b. |
