Part of the Kubota Repair Manuals.
This Kubota Workshop Manual covers the GH series gasoline engines: the GH120, GH130, GH170, GH170-1, GH250, GH280, GH340 and GH400. It runs to 104 pages under publication 97897-00915 and is written for teardown level service of these discontinued single cylinder engines.The manual moves from specifications, performance curves and dimensions into the mechanism of the engine body, lubricating, fuel, ignition and starting systems, then into disassembly and servicing for each. You get engine identification, troubleshooting for starting difficulty, servicing specifications, carburetor and governor adjustment, ignition checks and full circuit diagrams.With this PDF an owner or small engine mechanic can rebuild a GH engine, clean and set the carburetor, test the ignition, or chase a no start with exploded views and factory clearances instead of guesswork. Download it once and keep it on a phone, tablet or shop computer, and print the pages you need on the bench.
What's Inside This Kubota GH120–GH400 Series Manual
| System | Pages | Key Topics |
|---|---|---|
| Specifications | - | Engine Specifications (Model, Type, Total Displacement, Bore X Stroke, Continuous Horsepower, Maximum Horsepower, Maximum Torque, No-Load Maximum Speed, No-Load Minimum Speed, Compression Ratio) |
| Performance Curves | - | Gh120 (Brake Horsepower, Engine Speed, Fuel Consumption, Torque, Maximum Torque, Maximum Horsepower, Recommended Horsepower) |
| Dimensions | - | Gh120, Gh130, Gh170, Gh170-1, Gh250 Gh280, Gh340, Gh400, Gh400-2 |
| Feature | - | Cross Section (High Output and Low Fuel Consumption, Low Vibration and Low Noise), Contrast Between D.Q.P.S.G.I Types and R Type |
| Engine Body (Mechanism) | - | Mechanical Decompression System (at Engine: Start, Running) |
| Lubricating System (Mechanism) | - | Oil Pump, Relief Valve |
| Fuel System (Mechanism) | - | Carburetor (Main Carburetor System, Slow System, Float), Governor |
| Ignition System (Mechanism) | - | Transistor Magnet Ignition Type, Cdi Magnet Ignition Type |
| Starting System (Mechanism) | - | Starter Operation Except for GH340, GH400 (When: Main Switch Is Turned to Start, Engine Starts, Starter Switch Is Released), Starter Components (Except for GH340, GH400) |
| General | - | Engine Identification, Troubleshooting (Typical Troubles and Their Causes, In Cause of Difficulty with Engine Starting), Servicing Specifications (Engine Body) |
| Engine Body (Disassembly and Servicing) | - | Checking and Adjusting, Disassembling and Servicing (External Components, Cylinder Head, Piston, Connecting Rod and Crankshaft, Except for GH400, GH400 Only) |
| Lubricating System (GH400) | - | Checking, Disassembling and Assembling (Oil Pump, Relief Valve), Servicing (Oil Pump) |
| Fuel System (Disassembly and Servicing) | - | Checking and Adjusting Carburetor (Engine Speed, Engine Idling Speed), Checking and Adjusting Governor (Governor and Maximum No-Load Speed) |
| Ignition System (Disassembly and Servicing) | - | Checking Spark Plug (Spark Test), Checking Stop Switch (Switch Continuity), Checking Ignition Unit (Transistor Magnet Type, Cdi Magnet Type) |
| Starting System (Disassembly and Servicing) | - | Starter, Disassembling and Assembling (Recoil Starter, Starter), Servicing |
| Engine Circuit Diagram | - | GH120, GH170 Circuit Diagram (Wire Size and Color Indetification), GH130, GH170-1 GH250 GH280, GH340 GH400 Circuit Diagram (Wire Color), Component List |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| Spark Plug Torque | 9.8 to 24.5 N-m | p. 47 |
| GH120, GH130 | ||
| Rotor Mounting Nut Torque | 29.4 to 49.0 N-m | p. 47 |
| GH120, GH130, GH170, GH170-1 | ||
| Cylinder Head Screws Torque (M8 x 1.25) | 24.5 to 35.3 N-m | p. 47 |
| Connecting Rod Screws Torque (M7 x 1.0) | 13.7 to 19.6 N-m | p. 47 |
| Rocker Arm Rock Nut Torque (M6 x 0.5) | 7.8 to 12.7 N-m | p. 47 |
| GH120, GH130, GH170-1 | ||
| Crankcase 2 Screws Torque (M6 x 1.0) | 9.8 to 14.7 N-m | p. 47 |
| GH170, GH170-1 | ||
| Rotor Mounting Nut Torque | 58.8 to 73.6 N-m | p. 47 |
| GH170, GH250, GH280, GH340, GH400 | ||
| Crankcase 2 Screws Torque (M8 x 1.25) | 13.7 to 19.6 N-m | p. 47 |
| GH250, GH280 | ||
| Rotor Mounting Nut Torque | 68.6 to 83.4 N-m | p. 47 |
| Cylinder Head Screws Torque (M8 x 1.25) | 21.6 to 30.4 N-m | p. 47 |
| GH250, GH280, GH340, GH400 | ||
| Cylinder Head Screws Torque (M10 x 1.5) | 41.2 to 50.0 N-m | p. 47 |
| Connecting Rod Screws Torque (M8 x 1.25) | 23.5 to 29.4 N-m | p. 47 |
Kubota GH120–GH400 Series Common Problems This Manual Covers
Hard starting or no-start
The engine is hard to start or will not start, especially after storage. The General section lists typical troubles and their causes, including the causes of difficulty with engine starting, to guide the first checks.
Manual Section: General p. 35Stalling or surging under load
The engine starts but stalls, surges or runs unevenly, often from carburetor contamination, restricted fuel flow or a governor adjustment issue. The Fuel System disassembly section covers carburetor and governor checking and adjusting.
Manual Section: Fuel System (Disassembly and Servicing) p. 85No spark or weak ignition
Weak or absent spark points to ignition trouble. The Ignition System disassembly section covers spark plug testing, stop switch continuity and checking the transistor magnet and CDI ignition units.
Manual Section: Ignition System (Disassembly and Servicing) p. 88Low power or misfire
Low power, misfire or unstable combustion can come from internal wear, fouled plugs or valvetrain problems. The Engine Body disassembly section covers checking, adjusting and rebuilding the cylinder head, piston, connecting rod and crankshaft.
Manual Section: Engine Body (Disassembly and Servicing) p. 55Excessive vibration or knocking
Heavy vibration, noise or knocking usually indicates worn internal components or imbalance. The Engine Body disassembly section provides clearances, servicing specifications and reassembly steps to correct it.
Manual Section: Engine Body (Disassembly and Servicing) p. 55Recoil or electric starter failure
The recoil or electric starter fails to crank the engine. The Starting System disassembly section covers disassembling and assembling both the recoil starter and the electric starter, plus servicing.
Manual Section: Starting System (Disassembly and Servicing) p. 91Frequently Asked Questions
Which engines does this manual cover?
It covers the Kubota GH120, GH130, GH170, GH170-1, GH250, GH280, GH340 and GH400 gasoline engines under publication number 97897-00915, across 104 pages.
Does it list torque specifications?
Yes. The General section carries servicing specifications and tightening torques by model, for example the spark plug torque of 9.8 to 24.5 N-m, with cylinder head and connecting rod values alongside. p. 35
Can I use it to rebuild the carburetor and set the governor?
Yes. The Fuel System disassembly section covers checking and adjusting the carburetor and the governor, including idle speed and maximum no load speed. p. 85
Are circuit diagrams included?
Yes. The Engine Circuit Diagram section provides the wiring circuit diagrams with wire size and color identification and a component list for the GH series. p. 99
How quickly can I access this manual after buying?
A 104-page Workshop Manual in searchable PDF, ready the moment your checkout clears. Open it on a computer, tablet, or phone with no shipping wait.
Can I print specific sections of this Kubota GH120–GH400 Series Workshop Manual?
Yes. Print as many copies as you like; there are no restrictions. Plenty of mechanics run off just the section they need and carry it out to the shop floor.
Are hydraulic system diagrams in this Kubota GH120–GH400 Series Workshop Manual?
No. This manual does not include hydraulic system diagrams or schematics. It covers engine specifications, performance curves, wiring diagrams, and mechanical service procedures.
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