Yep, I would say the crank is junk. I know the engine is cute, but I wouldn't put too much effort into it. (Do a search here in the forum for Echo 16cc.)

The Echo 21 and 24cc engines weigh only a few ounces more but make tons more power. I have some for sale, both converted ready to fly, and not converted yet. PM me if interested.

AV8TOR