Patent ID: 6962096

Claim:
A casing of an engine comprising: a crankshaft; a shift input shaft and a shift output shaft; a clutch mounted at one end of the shift input shaft and a primary reduction gear that reduces the rotational speed of the crankshaft and transmits it to the clutch, said shift input shaft and said shift output shaft being arranged mutually in parallel; a crankcase for supporting the shift input shaft and the shift output shaft; a crankcase side cover having an inner end and an outer end, the inner end of the crankcase side cover being joined to one side end of the crankcase for covering the primary reduction gear; and a clutch cover joined to the outer end of the crankcase side cover, the clutch cover and the crankcase side cover forming a clutch chamber for housing the clutch, wherein an inside diameter of joined faces of a clutch enclosure portion of the crankcase side cover and the crankcase is set to be smaller than an outside diameter of a clutch outer of the clutch, and wherein joined faces of the clutch cover and the crankcase side cover, and also the joined faces of the crankcase side cover and the crankcase, surround an axis of a shift input shaft.