All 527 pages of this Honda TRX680FA service manual PDF point at one goal: getting your ATV back to factory spec, from carburetor teardown to the automatic transmission and torque converter. You get factory wiring diagrams, shift clutch hydraulic circuit schematics, and a troubleshooting chart that walks the automatic transmission from symptom to fix. Inside: self-diagnostic procedures for the Selectable 4WD system, error code charts, valve clearance checks, and a full maintenance schedule with intervals for oil, brakes, and tires. Refill the crankcase with 2.9 liters after draining and changing the filter, then set cold tire pressure to 30 kPa (4.4 psi) before the machine rolls out. Your quad is down and hunting season won't wait. Get the factory numbers, not forum guesses. Bookmarked and keyword-searchable; jump straight to the spec and start wrenching.
What's Inside This Honda TRX680FA/FGA, TRX650FA Manual
| System | Pages | Key Topics |
|---|---|---|
| General Information | 3-38 | Service Rules, Model Identification, General Specifications, Torque Values, Tools, Cable & Harness Routing |
| Frame/Body Panels/Exhaust System | 39-58 | Service Information, Troubleshooting, Body Panel Locations, Seat, Front Fender, Exhaust System |
| Maintenance | 59-81 | Maintenance Schedule, Engine Oil, Spark Plug, Valve Clearance, Brake System, Wheels/Tires |
| Lubrication System | 82-93 | Lubrication System Diagram, Service Information, Troubleshooting, Oil Pressure Check, Oil Pump, Oil Cooler |
| Fuel System | 94-116 | System Components, Troubleshooting, Carburetor Removal, Carburetor Disassembly/Inspection, Carburetor Assembly, Fuel Tank |
| Cooling System | 117-133 | System Flow Pattern, Troubleshooting, Coolant Replacement, Thermostat, Radiator/Cooling Fan, Water Pump |
| Engine Removal/Installation | 134-144 | System Components, Service Information, Engine Removal, Engine Installation |
| Cylinder Head/Valve/Camshaft | 145-166 | System Components, Troubleshooting, Cylinder Compression, Valve Guide Replacement, Camshaft Removal, Cylinder Head Assembly |
| Cylinder/Piston | 167-176 | System Components, Service Information, Troubleshooting, CYLINDER/PISTON Removal, CYLINDER/PISTON Installation |
| Alternator/Starter Clutch | 177-191 | System Components, Service Information, Troubleshooting, Recoil Starter, Alternator STATOR/STARTER Reduction Gears, FLYWHEEL/STARTER Clutch |
| Sub-Transmission/Gearshift Linkage | 192-207 | System Components, Service Information, Troubleshooting, Rear Crankcase Cover, Sub-Transmission, Gear Selector Lever Linkage |
| Automatic Transmission | 208-247 | System Components, Service Information, Troubleshooting, Oil Pressure Check, Shift Valve Body, Torque Converter Removal |
| Crankcase/Crankshaft/Balancer | 248-259 | System Components, Service Information, Troubleshooting, Crankcase Separation, Crankshaft, Crankcase Bearing Replacement |
| Front Wheels/Suspension/Steering | 260-289 | System Components, Service Information, Troubleshooting, Handlebar, Front Wheel, Wheel HUB/KNUCKLE |
| Rear Wheels/Suspension | 290-305 | System Components, Service Information, Troubleshooting, Rear Wheel, Wheel HUB/KNUCKLE, Rear Shock ABSORBER/SUSPENSION Arm |
| Brake System | 306-344 | System Components, Service Information, Troubleshooting, Brake Fluid REPLACEMENT/AIR Bleeding, Rear Brake PAD/DISC, Front Brake Master Cylinder |
| Front Driving Mechanism | 345-375 | System Components, Front Drive Shaft, Differential DISASSEMBLY/INSPECTION, Case Bearing Replacement, Differential Assembly, Differential Installation |
| Rear Driving Mechanism | 376-401 | System Components, Rear Drive Shaft, Final Drive DISASSEMBLY/INSPECTION, Case Bearing Replacement, Final Drive Assembly, Final Drive Installation |
| Battery/Charging System | 402-410 | Component Location, System Diagram, Battery, Charging System Inspection, Alternator Charging Coil, REGULATOR/RECTIFIER |
| Ignition System | 411-419 | Component Location, System Diagram, Ignition System Inspection, Ignition Coil, Ignition Timing |
| Electric Starter | 420-432 | Component Location, System Diagram, Starter Motor, Starter Relay Switch, Diode |
| Lights/Meters/Switches | 433-450 | Component Location, Headlight, Taillight, Ignition Switch, Handlebar Switch, Combination METER/REAR Vehicle Speed Sensor (Vss) |
| Selectable 4WD System | 451-463 | Component Location, System Diagram, Self-Diagnostic Function, Ecm Connector Inspection, Front Final Clutch, Rear Vehicle Speed Sensor (Vss) |
| Automatic Transmission System | 464-507 | Component Location, System Diagram, Troubleshooting Chart, Gear Position Switch, Gearshift Switch, Throttle Position (Tp) Sensor |
| Wiring Diagram | 508-510 | - |
| Technical Feature | 511-519 | Torque Converter, Hydraulic Valve Function, Shift Clutch Hydraulic Circuit and Operation, Automatic Transmission Performance Curve |
| Troubleshooting | 520-525 | Engine Does Not Start or Is Hard to Start, Engine Lacks Power, Poor Performance at Low and Idle Speed, Poor Performance at High Speed, Poor Handling |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Engine oil capacity After draining/filter change | 2.9 liters (3.1 US qt, 2.6 Imp qt) | p. 9 |
| Air filtration | Oiled urethane foam | p. 7 |
| Shoe lining thickness | 4.0 (0.16) | p. 12 |
| Minimum tire tread depth | 4 mm (0.16 in) | p. 11 |
| Cold tire pressure Standard | 30 kPa (0.30 kgf/cm², 4.4 psi) | p. 11 |
| Engine oil filter center bolt torque | 18 N·m (1.8 kgf·m, 13 lbf·ft) | p. 70 |
| Air cleaner | NOTE 1 | p. 61 |
| Brake pads wear | NOTE 1, 2 | p. 61 |
| O-rings for oil filter cover and center bolt | new | p. 70 |
| Engine oil leaks | Make sure there are no oil leaks. | p. 70 |
| Coolant leaks | Check to see if there are any coolant leaks when the coolant level decreases very rapidly. | p. 72 |
| Recoil starter driven pulley bolt | 108 N·m (11.0 kgf·m, 80 lbf·ft) | p. 179 |
Honda TRX680FA/FGA, TRX650FA Common Problems This Manual Covers
Honda TRX680FA engine cranks but won't start or starts hard after sitting in cold weather
Check the fuel line and pull the spark plug for a spark test, working through the troubleshooting procedures starting on page 520. Test cylinder compression next; you want 510 kPa at 390 rpm. Low compression points to tight valves, so measure intake clearance against the 0.15 mm spec on page 60.
Manual Section: Engine Does Not Start or Is Hard to Start p. 520Rough unstable idle after startup, engine hunts and stalls at low speed
Verify idle speed sits at 1,400 plus or minus 100 rpm before chasing anything else. Adjust the pilot screw and check for intake air leaks between the carburetor boot and cylinder head. Run a spark test and confirm ignition timing. If it still hunts, measure compression; 510 kPa at 390 rpm is the spec on page 10.
Manual Section: Poor Performance at Low and Idle SpeedOil or coolant leak spotted during pre-operation inspection, level drops between rides
Inspect the crankcase for external oil leaks using the lubrication troubleshooting steps on page 85, then pressure-check the coolant passages if the level drops fast. Drain and refill after fixing the source; oil capacity is 2.9 liters with a filter change. Fit new O-rings on the filter cover and torque the center bolt to 18 N·m, per page 70.
Manual Section: Lubrication System p. 85Brake lever feels soft or spongy, braking pulls unevenly side to side
Check the rear disc pads for wear and measure the front shoe lining; replace anything below the 4.0 mm service limit. Inspect lines and fittings for fluid leaks, then bleed the system following the brake procedures starting on page 306. When refitting the rear caliper, torque the retaining bolt to 23 N·m as shown on page 315.
Manual Section: Brake System p. 306Air filter and drain tube clogged with mud and dirt, engine bogs under throttle
Remove the air cleaner housing cover and pull the oiled urethane foam element; wash it, dry it, and re-oil it per the maintenance schedule on page 61. Clean out the drain tube, since trapped water ends up in the intake. While the seat is off, set tire pressures: 30 kPa front and 25 kPa rear, cold.
Manual Section: Maintenance p. 61Frequently Asked Questions
How do I reset a Honda TRX680FA error code?
To erase a problem code, first perform the retrieval procedures (page 24-8). Then, while the problem code is displayed, push the UP and DOWN shift switches simultaneously for 3 seconds or more. Once the erasure is complete, the blinking pattern will change to the erasure confirmation blink, and you can turn the ignition switch to "OFF". p. 471
What are the torque specifications for Honda TRX680FA engine bolts?
The torque specifications for Honda TRX680FA engine bolts vary by component. For example, the spark plug should be tightened to 18 N-m (1.8 kgf-m, 13 Ibf-ft), the engine oil drain bolt to 25 N-m (2.5 kgf-m, 18 Ibf-ft), and the cylinder head cover cap nut to 54 N-m (5.5 kgf-m, 40 Ibf-ft). p. 14
What do Honda TRX680FA error codes mean?
Honda TRX680FA error codes are indicated by the number of blinks of the "--" symbol on the gear position indicator, ranging from one to fourteen blinks. Each blink pattern corresponds to a specific problem code, such as "Problem code 1: System voltage" or "Problem code 2: Gear position switch", which helps identify the probable faulty part. p. 475
What are the replacement specifications for the Oil filter?
The manual indicates that the engine oil filter should be replaced as part of routine maintenance. The procedure involves draining the engine oil, removing the old filter, and installing a new oil filter, ensuring new O-rings are coated with oil and installed correctly (page 3-12). p. 60
What is the recommended engine oil capacity for the Honda TRX680FA?
The recommended engine oil capacity for the Honda TRX680FA varies depending on the service performed: 2.8 liters (3.0 US qt, 2.5 Imp qt) after draining, 2.9 liters (3.1 US qt, 2.6 Imp qt) after draining and filter change, and 4.1 liters (4.3 US qt, 3.6 Imp qt) after disassembly. p. 9
Is this Honda TRX680FA Service Manual a digital download?
You get a 527-page searchable PDF that downloads instantly after checkout. Open it on your laptop, tablet, or phone, and bring it right to the shop floor.
Can I print specific sections of this Honda TRX680FA manual?
Absolutely. No DRM or copy protection. Print the whole manual or just the pages you need. Any home or office printer works.
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