| 摘要 |
PROBLEM TO BE SOLVED: To improve power of a two-cycle engine by reducing the compression ratio in a crankcase, while restraining increase in the engine vibration caused by increase in the engine weight, complication of assembling processes, and increase in cost for parts. SOLUTION: A crank arm 62a constituting a crankshaft 6 of the two-cycle engine 1 of a crankcase compression-scavenging type and a counterweight 63a are formed in a nearly T-type when observed in the axial direction. An insertion member 10 made of a material having a smaller specific weight than the counterweight is fixed by externally fitting an annular member 64 in notched parts formed on both sides of the crank-arm. COPYRIGHT: (C)2005,JPO&NCIPI
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