Stihl MS 390 Chain Saw Specs

The Stihl MS 390 is either a heavy-duty chain saw or it's on the heavy-duty side of midrange saws, depending on who reviews it. Either way, it's a powerful saw suitable for anyone with a load of firewood to cut or farm maintenance to perform. Stihl began producing the saw in 1993 and no longer manufactures it -- it has been replaced by the MS 391.

Stihl recommends a conventional guide bar with a length from 16 to 25 inches (40 to 63 centimeters); if the bar has a sprocket nose, it can be as long as 30 inches (70 centimeters). Some users report that the saw doesn't perform well with a bar longer than 20 inches (50 centimeters). The engine is larger than comparable midrange Stihl saws, such as the MS 361. That that doesn't necessarily translate to more power, according to people who own more than one Stihl saw, because the engine design of comparable saws is different.

Engine displacement: 64.1 cubic centimeters (3.9 cubic inches).

Engine bore: 49 millimeters (1.93 inches).

Piston stroke: 34 millimeters (1.34 inches).

Weight without bar and chain: 5.9 kilograms (13 pounds).

The MS 390 engine takes a 50:1 fuel/oil mix, which is standard for modern two-stroke engines; when mixing a gallon of fuel, add 2.6 ounces of two-stroke engine oil. The fuel cap is on the side of the machine and has a safety lock feature, and the fuel line is protected by a replaceable filter inside the tank. You should replace it once a year.

Two types of air filters are available for the MS 390: the standard fabric filter and a nonwoven fleece filter for dusty conditions. The muffler on some models is fitted with a spark arrestor screen -- which is a fire-safety feature -- and this should be cleaned regularly to maintain engine performance.

All three carburetor adjustment screws are readily accessible -- unlike on many contemporary saws -- allowing you to adjust the engine speed at idle, low speed and high speed. The engine idle speed is 2,800 rpm, and its maximum speed is 13,000 rpm.

The Stihl MS 390 takes a Bosch WSR 6F or a NGK BPMR 7A Plug with a 0.02-inch (0.5-millimeter) electrode gap.

The manufacturer recommends using a Stihl Rollomatic guide bar, and while it recommends chains up to 25 inches in length, the preferred length is 20 inches (50 centimeters). Chain pitch is 3/8 inches.

The Stihl MS 390 incorporates may of the features of other Stihl chain saws, which include:

A side-accessible chain-tensioning screw.

A chain brake that stops the chain automatically in the event of kickback and can be activated by pushing back the handle guard.

An operator-presence lever that must be depressed before the throttle can be activated.

A gripping dog that bites into the wood being cut to prevent wandering and kickback.

In addition. the MS 390 has a dual choke setting -- one for summer and one for winter operation.