{HEAD ~ This slight opening} and closing creates a shock wave that aids the atomizing air and fuel mixing in the intake system prior to normal intake valve opening and enhances the scavenging of {TAIL ~ combustion gases} during the exhaust cycle 
{ HEAD ~ This slight opening } and closing creates a shock wave that aids the atomizing air and fuel mixing in the intake system prior to normal intake valve opening and enhances the scavenging of { TAIL ~ combustion gases } during the exhaust cycle
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH