Vehicle internal combustion engine

An internal combustion engine for a vehicle, comprising:

• a crankshaft;
• a main shaft;
• a counter shaft;
• an output shaft with a length substantially equal to a length of the counter shaft;
• and
• a shift drum adapted to switch a combination of gears on the main shaft and the counter shaft,
• wherein the internal combustion engine is a V-type internal combustion engine having cylinders arranged in a V-shape,
• the crankcase of the internal combustion engine includes vertically halved upper and lower case members,
• the shift drum is disposed in the upper case member in a position that is under a rear cylinder bank, above the counter shaft and the main shaft, and that is forward with respect to the counter shaft and rearward with respect to the main shaft, and
• said crankshaft, main shaft, counter shaft and output shaft being arranged in parallel in a crankcase, and
• when the engine is viewed from a direction parallel to axes of the crankshaft, the main shaft, the counter shaft, and the output shaft,
• the main shaft is seen to be disposed in a rearward direction of the vehicle with respect to the crankshaft, the counter shaft is seen to be disposed in the rearward direction of the vehicle with respect to the main shaft, and the output shaft is seen to be disposed below and in a forward direction of the vehicle with respect to the counter shaft,
• wherein the main shaft and the counter shaft are disposed on a horizontal mating surface between the upper and lower case members, and
• further comprising:
• an oil pump;
• a drive shaft of the oil pump located in a position under the rear cylinder bank and forward with respect to each of the main shaft and the output shaft;
• and
• a drive chain for transmitting power from the main shaft on the horizontal mating surface to the drive shaft of the oil pump.

An internal combustion engine for a vehicle comprising:

• a crankcase;
• a crankshaft, a main shaft, a counter shaft, and an output shaft arranged in parallel in the crankcase;
• wherein the internal combustion engine is a V-type internal combustion engine configured with a front bank cylinder and a rear cylinder bank arranged back and forth in a V-shape, with the rear cylinder bank tilted rearwardly,
• wherein the crankcase of the internal combustion engine includes an upper case member and a lower case member which are vertically halved, and
• the crankshaft, the main shaft, and the counter shaft are disposed on a horizontal mating surface between the upper and lower case members, and
• when the engine is viewed from a direction parallel to axes of the crankshaft, the main shaft, the counter shaft, and the output shaft,
• the main shaft is seen to be disposed in a rearward direction of the vehicle with respect to the crankshaft;
• the counter shaft is seen to be disposed in the rearward direction of the vehicle with respect to the main shaft;
• and
• the output shaft is seen to be disposed below and in a forward direction of the vehicle with respect to the counter shaft,
• the internal combustion engine further comprising:
• a shift drum, adapted to switch a combination of gears on the main shaft and the counter shaft, is disposed above main shaft and the counter shaft, and forward with respect to the counter shaft and rearward with respect to the main shaft, and
• the shift drum is disposed, in a side view, at a position below the rear cylinder bank in a back and forth direction of the engine,
• wherein a planar-shaped upper portion of the crankcase facing upwardly toward the rear cylinder bank is arranged to be directly above the shift drum and to be nearly parallel to the horizontal mating surface between the upper and lower case members.