1991–1995 Yamaha Moto-4 YFM350ERA ATV Service & Repair Manual (P/N LIT-11616-07-28)

This service manual covers maintenance, troubleshooting, and repair of the 1991–1995 Yamaha Moto-4 YFM350ERA, identified in the specifications as model code 3HP2. Its workshop chapters cover the engine, carburetor, shaft drive, chassis, and electrical systems.

• Engine overhaul: Engine removal, crankcase separation, cylinder-head repair, crankshaft inspection, primary and secondary clutch service, and transmission assembly.

• Carburetor and throttle controls: Mikuni BTM32SH disassembly, component inspection, float-height and fuel-level adjustment, coasting-enricher checks, and wire-cylinder service.

• Shaft-drive repair: Middle and final gear disassembly, pinion and ring-gear shim selection, universal-joint service, and gear-lash measurement.

• Brakes and chassis: Front drum brakes, rear disc brake, rear-axle inspection, steering and toe-in adjustment, shock absorbers, and swingarm bearings.

• Electrical troubleshooting: CDI ignition, starter circuits, charging, lighting, and indicator systems, with circuit diagrams, continuity checks, and component tests.

• Maintenance references: Periodic inspection schedules, compression testing, oil-pump limits, torque tables, engine lubrication diagrams, and cable-routing drawings.

Written as a mechanic’s reference, this manual assumes workshop skills and access to the special tools needed for internal engine and gear service.

Engine, Clutch, and Transmission Repair

The engine chapters provide separate inspection and assembly information for the cylinder head, valve seats and guides, rocker arms, piston, rings, crankshaft, and balancer gears. Compression-test interpretation helps relate abnormal readings to possible ring, valve, gasket, or carbon-deposit problems.

Clutch coverage distinguishes the primary centrifugal clutch from the secondary plate clutch. It includes shoe and friction-plate wear checks, clutch-plate warpage, spring inspection, and release-mechanism adjustment. Transmission coverage extends to shift forks, guide bars, gear dogs, shaft runout, and assembly orientation.

The cam-chain tensioner is automatic and requires no routine adjustment. The manual instead documents its inspection and installation, along with cam-sprocket alignment and valve-timing checks.

Mikuni Carburetor and Cable Controls

The carburetor sectional view identifies the main metering, starter, and float systems. Repair coverage includes the needle valve and seat, piston valve, jets, starter plunger, and coasting-enricher diaphragm.

Float-height inspection and running fuel-level measurement are treated separately. The wire-cylinder section also covers the sliders and cable connections between the throttle lever and carburetor, with checks for smooth operation after assembly.

Middle Gears, Final Drive, and Chassis

The drivetrain chapters explain shim selection using component markings, followed by gear-lash verification. They also cover ring-gear thrust clearance, stopper clearance, bearing housings, drive-shaft splines, and coupling inspection.

The middle-gear adjustment section warns that overtightening the bearing-housing bolts can reduce lash and damage the gears. This gives the shim calculations and measurement procedures a practical role when rebuilding the assembly.

Chassis procedures cover brake lining and pad inspection, rear brake-disc thickness and deflection, steering bearings, tie-rod geometry, and swingarm bearing replacement. Suspension coverage includes shock-absorber inspection and rear spring-preload adjustment. Follow the manual’s support precautions when removing the rear drive assembly or engine.

Ignition, Starting, and Charging Diagnosis

System-specific test charts address missing or intermittent spark, a starter that will not operate, charging faults, lighting failures, and indicator-light problems. The starting-circuit diagram explains the neutral, reverse, and front-brake interlocks, helping distinguish an interlock condition from a starter-component fault.

Electrical references include the charging-system circuit diagram and the YFM350ERA wiring diagram with wire-color codes and connector layouts. Charging diagnosis uses output-current and coil-resistance checks. Starter-motor coverage includes brush wear, commutator inspection, armature continuity, and insulation testing.

The troubleshooting chapter also addresses hard starting, poor idle and higher-speed performance, shifting faults, clutch slipping or dragging, overheating, and unstable handling.

Valve Clearances, Wear Limits, and Head-Bolt Data

These are a few examples of the inspection and assembly specifications included in the manual.

Cold intake-valve clearance is 0.06–0.10 mm. Piston-to-cylinder clearance is 0.04–0.06 mm, with a 0.1 mm service limit. The transmission main- and drive-axle deflection limit is 0.08 mm.

Cylinder-head assembly data distinguishes the oiled M10 bolts at 40 Nm from the M8 bolts at 20 Nm and specifies staged tightening.

PDF Bookmarks, Wiring Detail, and Page Breakdown

Chapter access and wiring detail: PDF text search is not available. Embedded bookmarks provide access to the service chapters and individual sections. Small wire-color and connector labels in the final wiring diagram are readable when enlarged; rotating that page also helps.

The download contains one English-language, printable 330-page PDF: 10 introductory, index, and contents pages; 319 pages of YFM350ERA service information and wiring diagrams; and one appended “Sub Transmission” page. All are included in the total; the appended page is a fragment rather than a complete additional manual.