L=Piston stroke in feet
A=Area of piston in square inches
N=Power strokes per minute
I)Crank Train: So what exactly are we talking
about when I say Crank train?
*Well its a combination of piston,piston speed
as well as ring width,crank case volume,
bearing surfaces etc...
Note: Think of it as a train with the tractor
being the crank itself diving the rods
pistons rings all depending upon each
component for optimum performance.
Each item effects the performance as a
whole. Everything in motion is part of the
A)Pistons and rings:
*Most pistons manufactured by the japanese
manufactures have a higher silicone content
than some aftermarket manufacturers. And
silicone content is the name of the game
when avoiding melting holes at higher
Temps. For that reason I use off the shelf
pistons unless ring width and flutter
becomes an issue....
*Ring width and flutter affect piston speed
and sealing along the cylinder bore.
Example: Standard rings will begin to flutter around
60,000ft/sec2 in most two stroke street bikes
or 7000RPM. So why use them? well they
provide longevity and sealing far superior
to the narrow racing ring which remains
stable towards 10,000RPM. There are even
kit rings that remain stable even higher in
the RPM range. But what you do lose is the
low RPM seal and durability.
So why use them?,...They perform along with
the crank @ Crank train allowing for higher
sustained power in the upper revs. But you
ride a modern GP machine so its been
designed far beyond the days of RD350s.
Never install circlips in the 9 or 3 oclock
positions! Remember how fast the piston
and ring are traveling? They will spring out
and catch an exhaust port,...or the wrist
pin will move out into a transfer port!