I had one tree I had to borrow a saw from a friend of mine to cut up. http://www.husqvarna.com/us/products/professional-chainsaws/395-xp-w/#specifications
Had to make two cuts from the root ball to 20' up the log. That was a pain in the butt to do but it was still easier than the alternative.
The worst part was having to buy a new chain for the saw as I hit a piece of metal. We think it was a steel jacketed bullet.
It was a big Sugar Maple tree.
The 36" bar would reach all,but 6" of the way through at the crown. The main branches were anywhere from 20 to 29" in diameter.
It came over in a windstorm that blow in from the east, it had stood for around.