STIHL 029, 039 Chainsaw Service & Repair Manual (P/N 1127 020 1210)

• 151-page PDF: 83-page 1992 STIHL Service Manual plus a 34-page July 2004 Spare Parts List; the parts list is repeated once in the file, for 117 unique pages.
• Covers clutch and chain-drive service, chain-brake disassembly and assembly, front- and side-chain-tensioner repair, bar-stud replacement, and chain-sprocket configurations.
• Details engine pressure and vacuum testing, oil-seal replacement without complete engine disassembly, engine removal, and cylinder, piston, piston-ring, and crankshaft repair.
• Includes breakerless-magneto fault tracing, ignition-module and flywheel service, ignition air-gap setup, rewind-starter repair, AV handle work, handle-housing removal, and Master Control repairs.
• Provides fuel-system troubleshooting, carburetor leakage testing and overhaul, Walbro and Zama differences, carburetor adjustment, and automatic-choke diagnosis for the control valve, bellows, filters, and lever system.
• Handles chain-oil pickup and tank-vent checks, oil-pump removal and service, component-specific torque tables, approved service compounds, and 29 special servicing tools with part numbers.
• Adds exploded parts assemblies for the cylinders, engine housing, oil pump and clutch, chain brake, ignition system, rewind starter, handle housing, and HD-series carburetors.

This factory STIHL workshop material covers the 029 and 039 single-cylinder two-stroke chain saws in the 1127 model family. Their construction and repair procedures are largely shared, while model and component differences are called out where they matter. The 029 is identified as the 54.1 cm³ version and the 039 as the 64.1 cm³ version. STIHL states that the service manual was intended for servicing dealers and staff, and its reliance on pressure/vacuum testers, torque tools, and model-specific service fixtures makes it best suited to technicians or experienced repairers with comparable shop equipment.

Engine, Ignition, and Drive Repairs

The engine chapter goes beyond routine maintenance. It covers crankcase leakage diagnosis, external oil-seal replacement, removal of the engine from the one-piece engine/fuel-tank housing, cylinder and piston work, piston-ring replacement, and crankshaft service. The crankshaft, connecting rod, and needle bearing are treated as a non-separable assembly, an important parts-ordering limit when any one of those components is damaged. Low-compression machines are also distinguished by an “N” suffix and require the matching special piston.

Drive-system coverage includes the clutch drum, spur and rim sprockets, centrifugal clutch, chain brake, both chain-tensioner layouts, and the conversion from front to side adjustment. Ignition material traces no-spark and running faults through the plug, wiring, contact spring, module, and flywheel. It also makes clear that electronic ignition timing is fixed rather than adjustable, while providing the checks and setup data needed to diagnose the system correctly.

Fuel, Automatic Choke, and Lubrication

The carburetor section covers removal, pressure testing, fuel-pump and metering-side service, inlet-needle and control-lever inspection, throttle and choke shaft work, and final adjustment. Zama procedures are used as the main example, with Walbro construction differences identified separately. The automatic-choke chapter is unusually detailed, with functional description, fault isolation, temperature-dependent checks, engine-housing/control-valve leakage tests, off-machine valve testing, bellows pressure testing, filter service, and lever-system setup.

Chain-lubrication repair includes the suction hose and pickup body, oil-tank vent valve, driven worm, adjustable pump, and internal pump parts. The fuel-system chapters also cover the tank vent, pickup body, fuel hose, and replacement of the combined fuel-tank/engine-housing assembly.

Diagrams, Parts Identification, and Repair Cautions

Visual references include the ignition-system troubleshooting chart, automatic-choke functional schematic and diagnostic flowchart, chain-drive assembly sequence, crankcase pressure/vacuum test setups, and exploded oil-pump/clutch and chain-brake assemblies. The July 2004 parts list identifies HD-19B carburetor parts, USA-only HD-18B and HD-21B applications, and the earlier HD-5 configuration.

One parts break can prevent a costly mismatch: the list separates the later 46 mm 029 piston/cylinder from the previous 45 mm build at machine number X 39 305 257 (46.97). It also distinguishes regional mufflers, filters, starter components, and Brazil-specific parts.

The manual warns that DG screws in polymer and light-alloy parts must re-enter the existing formed thread; cutting a second path can weaken the joint. It also cautions that unsupported pressure during automatic-choke lever installation can buckle the carburetor shafts. Ignition high voltage, the loaded rewind spring, the clutch, and the chain-brake mechanism all require normal workshop isolation and safe handling before repair work begins.