Stihl 025 Chainsaw
SERIES OR ASSEMBLY NUMBER:1123
ENGINE DISPLACEMENT:44.3 ccm (2.70 cu. in.)
NUMBER OF CYLINDERS:1
CYLINDER BORE:42 mm (1.65 in)
PISTON STROKE:32 mm (1.26 in.)
CYLINDER TYPE:Aluminum with chrome plated bore
INTAKE METHOD:Piston ported
MANUFACTURER ADVERTISED H.P.:3.0
OPERATOR CONFIGURATION:One Man operation
CONSTRUCTION:Injection molded plastic, die cast magnesium
CARBURETOR:ZAMA C1Q type
MAJOR REPAIR KIT:
MINOR REPAIR KIT:
AIR FILTER SYSTEM:Nylon mesh cartridge
STARTER TYPE:Automatic rewind
OIL PUMP:Automatic, gear driven, non adjustable
MAXIMUM ENGINE RPM:12,500
BREAKER POINT SETTING:none
FLYWHEEL/COIL AIR GAP:0.2 to 0.4 mm (0.008 to 0.016 in.)
SPARK PLUG TYPE:Bosch WSR6F, NGK BPMR7A, Champion RCJ7Y
SPARK PLUG GAP:0.51 mm (0.020 in.)
CRANKSHAFT MAIN BEARINGS:Ball
FUEL TANK CAPACITY:
FUEL OIL RATIO:50:1 with Stihl oil
RECOMMENDED FUEL OCTANE:Regular grade
MIX OIL SPECIFICATION:Stihl two-cycle chain saw mix oil
BAR MOUNT PATTERN:
SHORTEST GUIDE BAR SUPPLIED:
LONGEST GUIDE BAR SUPPLIED:
ILLUSTRATED PARTS LIST:Available from this website
SERVICE MANUAL:Available from this website
Fuel Mixture For Stihl 025 Chainsaw
Stihl specifies that the 025 be fueled only with unleaded gasoline and a high-quality oil intended for use in two-stroke engines at a ratio of 50 parts gasoline to 1 part oil. To achieve this ratio, combine 2.6 fluid ounces of oil with each gallon of gasoline, adding the oil to an appropriate mixing container first, followed by the gasoline.
Two-cycle engine oils are designed for high-performance engines such as those in chain saws, and they will help prevent problems such as pre-ignition and ring sticking.
Stihl also recommends the use of gasoline with a minimum octane rating of 89 in the 025. Use of gasoline with a lower octane rating, the manufacturer claims, increases the chance of pre-ignition, high engine operating temperatures and piston seizure.
Safety and Convenience Features
The Stihl 025 chainsaw is equipped with a chain brake that can be operated manually by the user, and it is also activated automatically by inertia when the hand guard in front of the handle moves suddenly toward the nose of the bar, as may happen when the saw kicks back.
The saw is equipped with vibration-damping motor mounts that reduce the amount of vibration transmitted from the running motor to the saw’s handles.