I just got through converting and souping up an Echo 21.2cc engine for my brother. We all look for the better 23.6cc engine, but this 21cc turned out pretty well.

Specs:

Port timings changed to:

Exhaust 150 degrees
Intake 143 degrees
Transfers 100 degrees

Free flowing muffler
9.5 mm carb "massaged" to 9.7 mm
Carb adapter opened up to match carb outlet
Deck clearance set to .020"
Frank Bowman top ring at .001" gap
Stock second ring

Running on Gas/Glow, after only one tank of fuel it turns an APC 14 x 8 at 9600 rpms!

I don't have other props on hand at the moment, but it should turn a 16 x 8 at over 8000 rpms. Not bad for a little 21cc, $10.00 engine...

It starts on the first flip nearly every time, and curiously, after about 20 starts it has never once started up backwards. My other Gas/Glow engines do occasionally start backwards if I'm a little lazy flipping the prop.

AV8TOR