I have 2 OS 140 RXs. The break in is pretty straight forward, as per the manual.
The origional rear bearing should be good for about 100 flights, then change to the 140RX- FI bearing (part # 29430010)
Use an OS-F plug and start with a 16x12 APC prop. Set the pipe long - about 22". I use 15% nitro fuel (Power Master with 18% oil - castor and synthetic blend). Open the needle 2 and 1/2 turns. Start the engine and slowly open the throttle to wide open, very rich - very smokey. If it is too rich slowly close the needle so that it will run WOT. Then slowly close the needle to bring the revs up for 30 second bursts, then open the needle again to the starting possition. Run just 3 to 5 minutes, shut it down and let it cool. Repeat the process for 3 tanks eventually closing the needle to full revs (8,200 RPM) and then back off 2-3 clicks, make sure there is pleanty of smoke.
Now set the idle at 1,500 RPM. Check the mid range tansition from idle. The low end needle ajustment should be OK at least for the first few flights and then only need a slight (1/8 of turn) lean. That completes the basic break in. After that you will be looking for a smooth mid range transition in flight. Much depends on the pipe you are using. You should be aiming for a about 8,200 RPM on an APC 16x13W, a 17x12 or a 15x13 3 blade. Some like a 4 blade. Search here for some good threads on 140 RX props and the 140 in general.
For any problems or questions come back to RCU and ask. There are people here with loads of experience on the 140RX.
For my money its still the most reliable, hastle free pattern engine available. I hope the 160FX I am moving on to is as good.

Good luck and a Happy Christmas!