1986–1991 Yamaha VMX12 V-Max Factory Service & Repair Manual (P/N 2EN-ME1)

This Yamaha VMX12 (V-Max 1200) factory service manual covers maintenance, diagnosis, and repair of the 2EN model. It is the first edition, March 1986, with cover code 2EN-ME1.

• Engine overhaul: Engine removal and installation, cylinder-head service, camshaft inspection, crankcase disassembly, and crankshaft and balancer-shaft bearing selection.

• Transmission and shaft drive: Clutch and shift-mechanism inspection, middle-gear setup, universal-joint service, final-drive overhaul, and gear-lash adjustment.

• Carburetion: Mikuni carburetor disassembly, diaphragm and piston-valve inspection, fuel-level adjustment, synchronization, and throttle-cable cylinder adjustment.

• Cooling system: Water-pump bearing and seal replacement, thermostatic-valve inspection, coolant-drain-valve service, radiator-cap testing, and cooling-system leak checks.

• Brakes and chassis: Caliper and master-cylinder repair, hydraulic-clutch service and bleeding, front-fork rebuilding, steering-head adjustment, and swingarm inspection.

• Electrical diagnosis: Starting, charging, TCI ignition, lighting, signal, fan, and fuel-pump circuits, supported by wiring diagrams and troubleshooting charts.

Written primarily for Yamaha dealers and qualified mechanics, the manual assumes a basic understanding of motorcycle repair concepts and procedures.

Engine Overhaul and Valve-Pad Adjustment

The engine chapter covers valve-guide replacement, valve-seat cutting and lapping, piston and ring inspection, oil-pump checks, and internal transmission inspection. Bearing-selection information explains how crankcase, crankshaft, and connecting-rod markings relate to the replacement bearing sizes.

Valve-clearance service uses removable adjusting pads, a pad-selection chart, and Tappet Adjusting Tool 90890-04105. Camshaft installation instructions distinguish the front and rear cylinder-bank timing marks.

The engine-in-frame service notes help determine whether engine removal is necessary for a clutch, carburetor, water-pump, or AC-magneto job.

Middle Gear and Final-Drive Setup

Middle-gear service separates drive-pinion shim selection, gear-lash adjustment, driven-pinion bearing replacement, and starting-torque checks. The final-drive section adds ring-gear positioning, stopper-clearance measurement, thrust-washer selection, and drive-shaft spline inspection.

The manual cautions that hammering the U-joint during middle-gear lash measurement can distort the driven-pinion collapsible collar and change starting torque, requiring collar replacement and driven-gear reassembly.

Shaft-drive troubleshooting relates hesitation, rumbling, whining, and clunking to possible bearing, gear-lash, gear-tooth, or drive-shaft faults.

Mikuni Carburetors and Cooling Components

The BDS35 Mikuni carburetor section includes a sectional view of the fuel and air passages. Inspection covers the coasting-enrichment valve, starter plungers, vacuum diaphragms, floats, and needle valves.

Its handling cautions explain how dropping or mishandling the fragile plastic piston valves can crack and weaken them. Fuel-level measurement and throttle-cable cylinder adjustment receive separate procedures.

The Coolant Flow drawing identifies the radiator, bypass connections, drain valve, thermostat, and water pump. Repair coverage extends to the pump’s mechanical seal, cylinder-head water-jacket joints, and radiator/conduit assembly.

Brakes, Suspension, and Steering

Brake and hydraulic-clutch sections cover cylinder inspection, seal replacement, reassembly, and air bleeding. Front-fork instructions address damper-rod removal, bush and seal replacement, and air-assisted suspension adjustment.

Steering-head bearing service and swingarm pivot checks are included. Rear-shock coverage addresses removal, inspection, preload and damping adjustment, and replacement of a defective assembly.

For brake bleeding and coolant service, follow the manual’s precautions concerning loss of braking performance and hot, pressurized coolant.

Electrical Fault Tracing and Routing Drawings

The VMX12 Circuit Diagram is supported by separate Charging System and Fuel Pump System circuit diagrams. Tests cover the starter motor, starting circuit cut-off relay, ignition coils, pickup coils, pressure sensor, rectifier/regulator, and battery.

Fuel-pump troubleshooting distinguishes failure after startup, failure of the initial priming cycle, and failure to stop after the fuel warning. The appendix supplies component torque tables, lubrication diagrams, and Cable Routing drawings for harnesses, cables, and hoses.

A Preview of Cooling and Generator Specifications

These examples are a small selection of the manual’s cooling and electrical reference data.

The coolant-replacement section specifies a total capacity of 3.05 L. The Hitachi FL130-04 AC generator has a nominal output of 14 V, 25 A at 5,000 r/min; separate sections provide charging-voltage and stator-coil resistance tests.

Searchable Text, Chapter Bookmarks, and PDF Contents

Search and diagram detail: The main text is searchable, and eight embedded bookmarks open the major chapters. Some labels within circuit drawings are outside the searchable text. Small wire-color codes and connector details require zooming for comfortable reading.

One printable, English-language 331-page PDF contains the manual. The total already includes six front-matter pages, seven chapter-divider pages, and the final unnumbered wiring-diagram page.