Cylinder No. 1 is front cylinder on right side of engine, as viewed from flywheel end. Cylinder No. 2 is front cylinder on left side of engine. Cylinders No. 1, 3 and 5 are on right side. Cylinders No. 2, 4 and 6 are on left side. See Fig 1 and Fig 2
Fig 1: Identifying Cylinder Numbering & Firing Order