Burned up a Husqvarna 359 the other day. This saw was in need of a few things and was a great saw for a long time. I put a new modded muffler, oil lines, crank seals and piston. It passed a vac test and I tuned it to 12500 rpm for the break in. Ran as it should for the first tank, and all the second till it died in a cut. I’m guessing it leaned it self out on a nearly empty tank or developed a leak. It was four stroking and never ran any different. Most pistons I've seen have a lot more damage on them from lean conditions and there wasn’t much of any transfer on the cylinder wall. The other cause that I could think of is just an overheating of the cylinder because of the muffler. I basically cut the top piece off the falling apart OEM muffler and welded it to the AM in the same location, leaving the AM opening alone. I’ve already got the saw running again, but wanted to get a few opinions before taking it back out. Thanks for everyone’s knowledge and opinions.