Air-cooled four-cylinder motorcycle engine - has two V=formation cylinder pairs with relative transverse angular and longitudinal offset

摘要

The air-cooled four-cylinder i.c. motorcycle engine has its crankshaft (10) extending in a longitudinal direction whilst the cylinders (1-4) are arranged in two pairs (1,2;3,4) each pair having its cylinders in V-formation. One pair (1,2) is angularly offset in transverse direction relative to, and arranged in front of, the other pair (3,4). The two cylinders of each pair may be at a relative angle of 90 deg. whilst the transverse offset between the two pairs is 30 deg. The common crank pin of one pair may lead that of the other pair by 180 deg. Successive cylinders (1-4) may fire with unequal intervals.