Once I found out that these engines are sub-7000rpm engines My thought went to
wondering why the big ports?

The 2100 series engines, 21cc, turn 9500 to 11000rpm according to Echo.
So why the fuss about large ports?

Also the carb size. I know there are people out there that can figure the CFM.
the stock carb flows now and how much the twin will flow.
It may run pretty good with a stock carb, but maybe not.

I have the parts now to build a stroker engine. I'm going to use the 25cc engine's crank which has a 2mm longer stroke
and the 21cc pistons which is 1.8mm smaller than the 23.6 cylinder. So it will still be a 21cc engine, times 2.

My hope is for an engine that will be more effecent because of the smaller ports and great low end and mid range because of the smaller ports and the longer stroke.

In theroy this should be the perfect all around engine.

I just need to get that stupid prop hub made so I can test it.

I'm just wondering what you guys think.