quarter liter. Cubic centimeter to cubic centimeter, a
two-stroke romps a four-stroke. Two-strokes have
one-tenth the moving parts of four-strokes. Two-strokes
cost less to maintain, are easier to work on and can be
rebuilt for one-quarter the price of a four-stroke engine.
Two-strokes cost less to produce and thus less to buy
because they require a lot fewer parts.
Back in 1997, the AMA passed a rule allowing four-strokes with displacements of up to 550cc to race in the
250 class. The intent of the rule was to encourage the
development of four-stroke engines. The 300cc
displacement advantage for thumpers was configured to
erase the differences between two-stroke and four-stroke
power—and as an admission that four-strokes were less
powerful than two-strokes when displacement was
considered. In 2002, four-stroke displacement for the 250
class was lowered to 450cc, while 125-class thumpers
were permanently etched at 250cc.
While way out front in moto two, Justin
Jones’ bike had an electrical problem and
he was forced to push it across the line.
Justin Jones ( 2), son of former AMA
Champion Gary Jones, made this
pass on Collier to take the first moto