The only engines that can be made to run in reverse (clockwise from the front) are those with a removeable front end (which isn't what the Enya 19X has). The front end has to be turned 90 degrees so the carb lays over on the exhaust side.

But because this can't be done on the Enya then all I can think of is that maybe the liner was fitted back to front so that the exhaust port is now on the transfer side. It's easy to check..the exhaust port is the one with it's top edge closest to the top of the liner (in other words it's the port that opens first when the piston's coming down). I don't know if these liners are pinned which would make it impossible to put in the wrong way.

dmac852...unless you've removed the piston from the rod in your teardown it can only go in one way. Look at the rod bushing and you'll see that one end has a small chamfer in the bush. This is the end that has to slide on the crank pin so that the chamfer is against the crank web. The chamfer gives a clearance for the tiny radius machined on the crankpin/crank web.