Whats the difference b/w PV and non-PV?

[fasterblaster09]

kinda stupid...but whats the difference between a PV engine and one thats not?.... thanks, neil

[250r4life]

there are plenty of posts about this already... however, pretty much the difference is a PV engine has a Valve that effects the exhaust port timing, remaining closed in lower RPMs to give more bottom end, and then opening in higher RPMs to continue to have that 2 stroke top end... it gives the 2 strokes a little more grunt and torque, and makes that power band hit a little smoother as to keep from breaking the tires loose...