All of the John Deere two-cylinder Tractors from the original Model D in 1924, to the last series
in 1958/1960 were called "Johnny Poppers" or "Poppin' Johnnies" because of
their distinctive exhaust note. During the course of two revolutions (a four-stroke cycle) of
the engine (720 degrees) the first cylinder fires at 0 degrees, the
second at 180 degrees, then the engine coasts 540 degrees until it
fires again beginning the next cycle.|
But why wouldn't it be better to have one cylinder fire each 360 degrees and even out the power strokes? Because that would necessitate having the crankshaft throws for BOTH pistons on the SAME side of the crankshaft at the same time. This means the weight of BOTH pistons would always be shifting back and forth together, much the same as the weight of a single large piston does, in a "one-lunger". Just think about how one of THOSE babies shakes when it fires!! The alternating pistons on a "Poppin' Johnny" allow it to run MUCH more smoothly!!
So...... What Model is a Johnny Popper?
The Model D, GP, A, B, G, H, L, LA, M, and R. The 40, 50, 60, 70 and 80; the 320, 420, 520, 620, 720, and 820; and the last series, the 330, 430, 530, 630, 730, and 830.
Find out how to tell them apart, right here:
Which Johnny Popper IS that?
(Letter Series) (1st Number Series) (2nd Number Series) (3rd Number Series)