Don't blow hard. Your neighbor didn't work into retirement as a well-respected local faller by cutting down 18" trees for a fireplace insert. 50cc saws are designed for it you're a joke. Go plant trees.
Actually 14 to 27 inch trees are the most commonly cut today for timber. REAL production fallers, not weekend hacks, pack a 460 with 32 inch bar for that. Flatlanders don't know such things. Here's a typical commercial thinning unit. This guy is not using a fru fru little boy saw.