crankcase 21 a and a lower crankcase 21 b four main cylinder bodies not shown can be integrally formed with each other on the upper crankcase 21 a of the crankcase 21 a cylinder head 23 tilts forwardly and thus forms a front bank 51 another cylinder head 24 tilts rearwardly and thus forms a rear bank 52 the cylinder heads 23 24 can be mounted to the topside of the main cylinder body the front bank 51 can be an example of a u201c first bank u201d and the rear bank 52 can be an example of a u201c second bank u201d however as used herein the identification of any component as u201c first u201d or u201c second u201d are merely arbitrary labels used solely for purposes of convenience similarly the cylinder head 23 can be an example of a u201c first cylinder head u201d and the cylinder head 24 can be an example of a u201c second cylinder head u201d top covers 40 a and 40 b can be attached to the topside of the cylinder heads 23 and 24 respectively the crankshaft 22 can have two sprockets 22 a and 22 b as shown in fig3 however other sprockets can also be used fig2 shows that a balance weight 41 a crankshaft 22 a primary shaft 42 and a secondary shaft 43 can be placed in order from front to back along a mating face between the upper crankcase 21 a and the lower crankcase 21 b the balance weight 41 rotates at the same speed as the crankshaft 22 but in a direction reverse the main function of the balance weight 41 is to absorb the primary vibrations.