I may start the engine at low throttle (if it has one) for safety reasons but then I go immediately to high throttle and adjust the needle for a very rich 2cycle. The reason for this is to get the engine up to temperature in a hurry so that the cylinder expands enough to relieve the pinch at top dead center. I start checking immediately for any signs of stress from the engine. Even though I have an IR temp probe I trust my calibrated fingers more for checking head, bearing temperature. After about 30 seconds to a minute I would guess, when I think the engine is up to temperature I shut it down and let it cool off. I repeat this about 20 times (thermal cycling) and if the engine hasn't shown any signs of stress I'll lean it out to about 3 to 4 hundred rpm below peak and let it run for a couple of minutes looking for stress or the temperature to start drifting up. I do all of this on a slightly undersized prop to keep the engine load a little low and avoid sudden temp run up. If the engine seems to be comfy with all this it's ready to go flying with the needle set to an over rich 2 cycle for a few flights.

On ringed engines I start them at 1/4 throttle and bring them up to a very rich 6000RPM and let it run out a tank of fuel. This is trying to get the ring seated. If nothing ugly is indicated on the next tank I open the throttle with a very rich needle. If things seem to be running nice and cool I'll lean it out to a very fast 4 cycle, just breaking into a 2 cycle. If every thing seems to be good after about a half tank I'll lean it a little more and start thermal cycling as above.

I basically used this procedure on iron liners with iron or aluminum pistons. If they didn't have a throttle then I just lit them off with a very rich needle. When the ABC's first came out my first experience with them was on Super Tigre 15s I was using in control line goodyear raceing. I tried to break them in just like an iron liner. I went thru several rods before I figured out what I was doing wrong.

Denis