The logo was developed over a period of time. It is the intellectual property of Mike Shelby.
First of all, the outer green ring symbolizes the flywheel on a John Deere two cylinder horizontal engine.
The inner circular wedges of different colors represent the otto cycle of a four cycle combustion engine.
Turning counter-clockwise, the blue segment represents the cool air intake into the cylinder; yellow is next, the compression stroke. Next, in succession, red represents the expansion, or power stoke of combustion, and last, brown represents the expelling of spent combustion gas on the exhaust stroke.
All tolled, these cycles require two complete revolutions of the crankshaft per cylinder.
Its helpful to remember that the flywheel side cylinder leads the pulley side cylinder by 180 degrees (half a turn) in the cycle of events of a John Deere Two-Cylinder engine.
The firing order is 1-2-skip-skip-1-2-skip-skip……