To prevent the copper bushing coming out on the conrod, you can plated the material rather than forcing 2 object together.

Regarding to the cylinder question. Here are some of my own opinion ( I am not a engine manufacturer and is not in the machinary industry. I just have an genuine interest in model engine production.)

Even the best CNC machine we have today, the manufacturing tolerance is about +/- 0.02mm, unless you start doing machining under control temp, atm etc. But the production cost willl be very very expensive. being massly produced engien, at novarossi etc I don't think every piston and sleeve is made to spec. Pick up a caliper or if you have a height guage and meaure the port on the sleeve. it is at different height from sleeve to sleeve. Some of the line aren't even cut straight. The inside of sleeve and piston is not in perfect roundness (+/- 0.0015). In fact it is not very round at all ( some of you will argue it is made to be elliptical on purpose, but trust me at the cost these engines are exported out of italy, they are not made to be elliptical on purpose).

Personally I think lapping or grinding on the sleeve is better than working on sleeve. because when the engine heats up, the piston usually expands more (that;s why it seizes), working on cylinder making sure it is round will enable the piston to "grow" into something good ( the secret in all modified engien is piston and sleeve fit, not the extra cut on the transfer port). If you work on the piston and make sure it is round but the cylinder is not...... more friction and leakage may result.

Yes cylinder taper is very important. But honing cannot reproduce the tapering. Honing simply removes the coating on the inside of the cylinder ( but the honing stone follows the basic geometry from the brass liner, in other words, if the cylinder is not round, it will not be round). Honing produces the crossweb surface finishing you see on novarossi, rb, jp engine. So see, they are massly produced, not that accurate as you guys have thought.

Grinding can correct any defect in the linder, make sure it is perfectly round and also maintains the taper. But is would be best to grind both piston and sleeve so both are in perfect roundness.

Correct me if i am wrong, any suggestions.....