I am working on a 1948 Villiers MK25C 147cc two cycle engine with a 55mm bore and 62mm stroke. My particular engine must have had a lot of hours on it because so much carbon built up behind the rings that the rings wore thin enough to jump past the pins which keep the rings in place. It did not cause any major failure, but it scored the cylinder a bit. I am mainly concerned about the big end of the connecting rod bearing. This particular engine uses a three piece crankshaft and a one piece connecting rod with brass and steel needle bearings. You have to press the crankpin out to replace the needle bearings. I chucked the crankshaft in my lathe, locked the spindle and measured 0.003" of slop in the big end of the connecting rod bearing off the top of the connecting rod. I cannot find any literature which says what the running clearance should be. Based on the fact that this engine runs on ~10:1 oil mix, I would imagine the play in the big end of the rod should be 0 to 0.001". The side to side clearance is excessive so i wonder how the thrust faces of the rod look like, if there are any. I would like to know how to proceed with replacing the connecting rod bearings, as the crankpin does not appear to be pinned on either end. It may require a special alignment jig which I do not have for re-assembly. I have already purchased new big end ball bearings for the crankshaft, and some brass stock to make new sealing bushings out of. Secondly I cannot seem to find any piston/cylinder clearance specs for this engine. The ring landings on my piston are wore out, so I am either going to have to find a replacement standard piston or go oversize. I would much rather go oversize to eliminate all of the scratches in the cylinder. Lastly does anyone have any recommendations on finding parts for these engines? I have contacted Villiersparts.co.uk and Meetens. I just heard back from George @ Villiersparts, he is pretty confident that he has the parts I am looking for, but says that the specs I am looking for are not available. Surely someone has actually rebuilt one of these engines before. This particular engine appear to be very common in England and Australia on Allen Oxford motor scythes and Howard Bantam Rotavators.