he MS 311 is a high-tech workhorse with a step up in horsepower and features over the MS 291. With our improved engine technology, you get higher fuel economy for longer run times. The MS 311 also has larger fuel and oil tanks for even longer extended use. You'll stay productive while you're saving money on fuel. With the MS 311 fuel-efficient, high-powered engine, you'll reduce your down time on the job so you can enjoy your own down time when the job is done.