ORIGINAL: BMatthews
Yes you can enlarge the cross section area of a basic twin flute design but if it's on a reed engine I doubt you'll see a LOT of difference. You can easily get more response through careful fitting and parts selection and using the right head and fuel.
Actually, I did a few simple tests a number of years back. On a stock black widow dual bypass cylinder, I raised the bypass port timing up to ALLMOST (but not quite) level with the exhaust port. I gained an average of 1200 to 1500 rpms!! Easy mod.
And as for the porting, if you include the old time (space bug/sbjr, etc) there are many different types of port cuts - more than mentioned here anyway... as some have vastly different tops of the bypass, as well as there being single, double and triple cut bypass'...
AJC