ORIGINAL: TEDDYWILKK
I WANT TO PUT A REED BOX ON MY TORO SO I CAN GET A GREATER DURATION WITHOUT THE REVERSION. DOES ANYONE KNOW WHAT THE PORT TIMING IS ON THESE RYOBI'S WITH THE REEDS. MANUFATURER MUST HAVE THOUGHT THEY WERE NESSARY BUT THE OTHERS DONT. WHAT SECRET PORT STUFF ARE THEY DOING TO THESE ENGINES?
FARMER TED
A normal reed valve engine has no intake "timing" per se. As mentioned, the reed opens any time the pressure is lower than atmospheric in the crankcase, and closes when it is higher. As such, it limits reversion and generally gives a more torquey and tractable power band. However, for higher rpms and horsepower, the reed assembly can be a restriction to airflow and can limit horsepower. High tech reed systems with multiple reeds, etc. have been designed to try and circumvent this problem.
AV8TOR