i have always gaped the plugs at 20 an they work fine. never had to repase a plug in an airplane engine. i know it isnt aircraft , but i have 13 chainsaws,,,1 is a stile. i havent replassed more thaN 4 plugs in years of sawing. i heat with wood and sell lots and only the sm,all saws hav ever need a plug. these huskys just run and run. nor have i ever had to adujust a carb once they are set right. i jusd used a 20 year old model 38 huskey for the first time in about 3 years. it was put away full of gas,,i just shoke it to mix the oil and it started just fine. break in ?,,,let them warm up for a minute and saw away. my gigantk huskey , the bigest production saw there is gets used maybe once a year,,,it starts right up and is put away,,,nuthing special. 5 of my saws are sitting out in a rain storm on the back of one of my farm tractors right now,,,they will run perfectly when the rain stops. what im trying to say,,,dont get all hyper asbout these small 2 cyl engines,,,threy dont need all kinds of b. s. to keep them riunning,,,i would never leave my sig or balsa usa gas cubs out in the rain,,,hehe. both have 20 tyear old gas engines that have never had more than a squirt ov syn motor oil in them when put away for the winter asnd both sdtill have the original plugs,...nor have i ever adjusted the carb jets since the first flights. tinkering has caused many good engines to go bad ! i use syn oil at 10 % morew than the raecomended ratio,,,my 2 cents,,,hehe