turbo sizing

[bruce plecan]

There seems to be alot of talk about reed valves/cages.  I don't
know how much things have changed lately, but it used to be
that at high rpm they "floated to a full open posistion".  There
was just no way to have them open and close fast enough.
They only worked til you got past most of the reversion levels
(rpm wise).   I'd tired some f-glass, and ss ones, but the only
way I got much of a boost was porting the cages out and bending
the pedal stops, so when they hung open the was a max amount
of open window.  

IMHO when you raise the boost levels you increase the back pressure
and then the cylinder won't purge itself.  unless there is a "check valve"
in the system.  A four stroke has the piston to displace the exhuast gases
out off the cylinder, a 2 stroke only has the pressure of the burnt
gases as the port opens, and both the int, and ex are both open for
a long time.  If there is enough back pressure then it is wasy to prevent
any intake tract flow.
Bruce    nacelp at bright.net