roostersgt
Addicted to ArboristSite
It has everything to do with viscosity and mixture density. Carb jets and mixture can only be metered through jets and passages properly at a certain viscosity. Jetting is calibrated for a specific flow under specific variables. 40:1 is a negligible difference but the principle still stands. 50:1 is an industry standard and has been for years, any mixture richer then that is a waste of oil and a cause for increased carbon deposit and plug fouling. Choosing not to understand this is your choice.
There doesn't appear to be an "industry standard". The following manufacturers require 40:1
Troy Bilt
Poulan
Craftsman
McCulloch
These manufacturers require 50:1
Stihl
Husqvarna
Echo
Ryobi
Shindawa
Maruyama
There may be other, but I think my point has been made. A lot of saws, and I mean a lot of saws have been running just fine on a variety of fuel mixes for a long time. Quality of oil and tuning is key.
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