ms 260, why a pro saw?

[zackman1801]

my question for you guys is, why is the MS 260 rated by stihl a "Professional use saw" when the Ms310, and ms290 are larger, have more ccs, horsepower and all. i dont understand how a 50cc saw can be considered a pro saw and a 59 cc can be considered homeowner? it makes little sense. can anyone tell me. is the 310 made differently?

[joe_indi]

The Stihl range of saws are categorized as non professional and professional.
Under the former there are the Compact and All Round saws.
The MS 310,290 and 390 are all round saws.

The basic difference between a Stihl professional and non professional saw is the design.
The former has a vertically split crankcase made of of magnesium alloy, which also houses the oil tank.The latter  has a horizontally split shortblock.Here the engine housing including the oil tank and fuel tank are a separate piece made of reinforced polymer.
The engine block is made up of just a cylinder and an engine pan.
It was easy to distinguish between  non professional and professional Stihl saws prior to the introduction of the 'MS' before the model number instead of '0' .
Non professional saws had odd number and professional saws had even numbers.
017, 023, 025,029,039, etc were non professional.
020, 024, 026, 028, 036, 038, 044,046, 066, 088 etc were professional.
The exception being the 018, which was a non professional model.
The engine cc has nothing to do with the classification.
A professional 020 (present day MS200) has a 35.2cc engine while as a non professional 039 (present day MS390 has a 64.1cc engine.

The magnesium alloy crankcase aids in keeping the engine cooler for all day long use, which a professional saw would require, irrespective of its size.

Joe

[jokers]

Power to weight ratio is another important distinction between Pro and everything else, as well as mean time between failures(mtbf). The 260, both the model labelled Pro and the non-Pro labelled version, are pro saws with better P/W than the 290, probably better than the 310 and maybe even the 390 although I`ve never checked, but nonetheless, the 310 and 390 are built on the same non-pro platform as the 290.

Put enough hours on a 260 to run the compression down to where the saw doesn`t work well any longer and it`s a simple and relatively cheap proposition to freshen it up with new rings and maybe a piston under extreme circumstances. It`s quite a bit more costly from a labor perspective to do the same job on the 290 et al.