Maybe i should send you my cylinder , and you'll understand where i'm coming from, and yes that is true, they do have a LITTLE chamfer on them but not enouph, also the cylinder is cheap made, that it don't matter if they are chamfered or not , when heat strikes that is the killer. All it takes is for 1 little piece of metal to be bounced around into the cylinder to ruin the sleeve and piston and rings untill the piece get shot out the exhaust or sticks into the piston. Also to answer the first response, 2 pistons, 1 carb, 2 sets of rings, Idler pulley, machine work on the cylinder, head work due to stripped spark plug, 1 throttle cable, 1 clutch cable, complete gasket kit. shall i go on. face it these engines are unreliable and you have to spend the $$$ to keep them runnin just as stated on here from other peoples post. 2 strokes are going to be exempt down the road. Myabe you got a good cylinder but they are not all the same, I'm sure other people who have these engines can back me up. I know one person on here i won't mention any names, but went thru 3 dax 70 engines and gave up on them , and i wouldn't blame him, all due to piston and cylinder problems. I'm not trying to cause problems, but trying to make people aware of problems with these engines. Of course you are trying to defend these engines, that is only because of the sales for distributors. I'm sure if you had a bad engine or a couple bad engines you would be venting to. Sorry . MO