RE: Irvine Engines
earlwb
The rod in your engine is fitted the wrong way round which means the piston may be too which means the ring gap may be in the wrong position. The photo showed a chamfer in the bush on the plain side of the rod which would mean the logo side faces to the rear. But just to be sure, and seeing I have a brand new Irvine similar to yours (except rear exhaust) I pulled the backplate for a look.