boyesen reeds have a tendency to make a bike run richer...i agree with everything above except "running rich has to do with jetting. the only way reeds would make it run rich would be if you downgraded"
thats not an acurate statement. and xima i believe your correct..or vise versa !! ..lol
The whole cycle can be explained as follows:
1) As the piston moves from bottom dead center to top dead center it creates a
vacuum to draw the fuel / air mixture through the carburetor and past the reed valve assembly.
2) The piston moves down from top dead center to bottom dead center. The reed closes, causing the pressure to build in the cylinder. The movement of the piston uncovers the intake port and pressurized the fuel / air mixture.
3) The piston now moves up from bottom dead center to top dead center, effectively ending a cycle and starting another. The spark plug ignites the compressed mixture, sending piston back down.
4) At this point the piston uncovers the exhaust port, allowing the spent gasses to escape. As it continues to bottom dead center, it uncovers the intake port and allows the fuel / air mixture through the carburetor and past the reed valve assembly.
A highly tuned two-stroke engine produces a tremendous amount of power per cubic centimeter, and is still effectively raced against larger capacity machines in dirt racing, where lightweight is valued more than raw horsepower. Unfortunately, two-strokes do emit more pollutants than four-strokes, are louder, and tend to use more gasoline. It is unlikely the design can be sufficiently altered to meet current emission control standards, so fewer and fewer two-strokes will be made in the future.
and thats the only damn reason that two strokes are becomming absolete..it reallk SUCKS
before i bought my yz i had a 450f and hated it, traded it back in for the two stroke