reed valves?

[overkill131313]

ok I dont consider myself dumb BUT! what are read valves on a 550 polaris fan cooled engine? well I took off the carbs and can see my piston going up and down. the engine has factory stickers that say reed valves. I believe these engines are piston ported not reed valves so what's up?

 

[overkill131313]

looking at the part mannual it looks like there is a reed valve in the cases, not between the carb and the piston? im still lost but since there is no reply I guess I dont feel stupid lol.