Yamaha YFM350ER Moto 4 ATV Service Manual Set, 1987–1995 (P/N LIT-11616-05-38)

The supplements update the YFM350ERT base manual, with each later supplement also requiring the preceding supplements. The A–G volume is a separate full service manual with YFM350ERA specifications and procedures.

PDF Navigation, Wiring Detail and Page Counts

Search and bookmarks: Only the early PDF's added cover has searchable text; its workshop pages and the entire later PDF are not searchable. Both PDFs have chapter and section bookmarks, although “Back to Index” points to a separate Main.pdf that is not included.

Diagram readability: Small wire-color and connector labels require magnification for clear reading.

The ZIP download contains two printable PDFs totaling 661 pages: 327 pages in the 1987–1990 file and 334 in the 1991–1995 file. This total includes one added compilation cover in the early PDF; publication covers, blank pages and rear covers are also included in the page counts.

Engine, Shaft Drive and Electrical Repairs

The topics below are a selection of the included content. Further examples include fuel-cock servicing and throttle-cable wire-cylinder disassembly and inspection.

• Engine overhaul: Removal and installation, cylinder-head and valve work, piston and crankshaft inspection, crankcase separation, oil-pump service, cam timing and starter systems.
• Transmission and clutch: Disassembly, inspection and assembly of the dual-range gearbox, shift mechanism, primary centrifugal clutch and secondary clutch, with adjustment and wear specifications.
• Shaft-drive service: Middle-gear and final-drive disassembly, pinion and ring-gear inspection, shim selection, gear-lash measurement, drive-shaft checks and fault diagnosis.
• Carburetion: Mikuni BTM32SH removal, disassembly, inspection, assembly and installation, supported by sectional drawings and fuel-level adjustment procedures.
• Chassis repair: Front and rear brakes, steering and tie-rods, lower arms, shocks, swingarm, wheels, hubs, rear axle, bearings and control cables.
• Electrical diagnosis: CDI ignition, starter cut-off and neutral/reverse interlocks, charging, lighting, indicator and accessory circuits, plus relay and starter-motor tests.
• Maintenance data: Periodic checks and adjustments, torque tables, lubricant and capacity charts, wear limits, electrical test specifications, lubrication diagrams and conversion tables.

Written for Yamaha dealers and qualified mechanics, these publications assume basic mechanical knowledge and access to the specified tools.

Variant Identification and Supplement Changes

Build identification: Model-code, VIN and engine-starting-number tables distinguish 1YW, 2VA, 3HP and 3HP2 builds. They identify JY41YW00, JY42VAW0 and JY43HPW0 vehicle prefixes, including the ERA starting-number pair JY43HPW0*LC024101 / 3HP-024101.

Updated procedures: ERU material includes oil-temperature display testing and revised high-range gearing; ERW updates cover front wheels, rear-axle work and the axle-nut wrench. ERA material updates brake controls, cable routing and electrical specifications, helping match procedures to the fitted build before selecting parts or repair methods.

Engine Overhaul and Routine Service

Overhaul depth: The air-cooled SOHC single is covered from removal through top-end, crankcase and crankshaft work to timed reassembly. Oil-flow diagrams, oil-cooler connections and temperature checks address its lubrication and cooling arrangements.

Periodic checks: Procedures include valve-clearance, compression and ignition-timing checks; throttle, carburetor, brake, clutch and toe-in adjustments; and suspension, wheel-bearing and electrical inspections. Cam-chain tension is automatic; the overhaul sections cover tensioner inspection.

Starter coverage: Electric and recoil starters are treated where fitted; ERW and ERA specifications list electric starting.

The crankcase procedures warn against forcing the halves apart unevenly, which can damage their mating surfaces.

Middle Gears and Final Drive Setup

Measured assembly: Pinion and ring-gear shim selection, thrust-washer selection and dial-gauge lash checks connect component replacement to final setup. Overtightening the middle-gear bearing housing can leave insufficient lash and damage gear teeth.

Exploded drive-unit views and shaft-drive symptom charts support inspection of noisy, jerking or locked drive components.

Wiring, Test Charts and Workshop Tools

Circuit tracing: Full ERT and ERA wiring diagrams accompany starting, charging, ignition and lighting circuit diagrams, the ERU oil-temperature test chart and cable-routing drawings. Relay continuity and coil-resistance tests support component diagnosis before replacement.

Special tools: Procedures identify the crankcase separator YU-01135 / 90890-01135, final-gear lash tool YM-01231 / 90890-01231, rear-axle nut wrench YM-37132, and pocket tester YU-03112 / 90890-03112.

Battery and charging data, ignition-coil resistance specifications, clutch and transmission limits, chassis wear specifications and component-specific tightening torques accompany the repair procedures.

Securely support the ATV before wheel, axle, brake, suspension, or shaft-drive repair. Electrical and starter procedures should be performed with the battery isolated where the manual calls for it, and the manual's warnings for hot oil, spring-loaded parts, rotating assemblies, pullers, presses, and striking tools should be followed throughout the work.

Selected Gear-Lash and Ignition Test Values

For the YFM350ERA final drive, the manual specifies 0.1–0.2 mm gear lash, with 0.2–0.4 mm at the specified measuring tool. These readings depend on the measurement setup described alongside the shim-selection procedures.

YFM350ERA ignition-coil checks specify 0.36–0.48 Ω primary resistance at 20°C and 5.44–7.36 kΩ secondary resistance at 20°C. The test diagrams identify the respective lead-terminal, coil-base and spark-plug-lead connections.