STIHL MS 291 Chainsaw | Fuel Efficient Chainsaws Another high-tech STIHL chainsaw, the MS 291 is built around one of our new fuel-saving engines with longer run times and lower emissions. And with an advanced pre-separation air filtration system, your air filter can last up to five times longer. Another great feature is an advanced anti-vibration system to reduce user fatigue.4.4/5(321)[PDF] STIHL MS 271, 291 Owners Instruction Manual MS 271, MS 271 C, MS 291, MS 291 C English 26 WARNING Use only identical STIHL replacement parts for maintenance and repair. Use of non-STIHL parts may cause serious or fatal injury. Strictly follow the maintenance and repair instructions in the appropriate section of your instruction manual.