Chainsaw Repair

About the only saw engines I have found with high carbon build up are those the oiling system are open to the crankcase such as impulse operated McCullochs .That's because eventualy they all leak a little bit and suck chain oil into the cylinder.You can't totally burn chain oil .

As far as heavy mix ratios no kidding I've torn down old saws I know had been ran on 16 to one using motor oil and they were virtually carbon free .They had sat on a barn floor for 30 years to boot .