Piston Lapping

I read about piston lapping the cox engines to loosen the piston to cylinder fit and get better performance. I used a piece of clear vinyl tubing,3M white rubbing compound and CRC 6-56 oil. I placed the piston conrod inside the vinyl tubing and saw where the hole of the rod was. using an awl I punched a hole about 1/16 inch lower so the tubing would hold the piston firmly. Put a mixture of oil and rubbing compound in the cylinder and worked the piston back and forth giving it a small twist every so often. I did that for a while then I cleaned the piston and cylinder it was still tight so I did a little more,I cleaned and tried again. the idea is to go slowly and check often to avoid damaging your P/L set. here are some pics.
                                                                                                                            Juan