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