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Honda GV400 Engine

The Honda GV400 is a 4-stroke L-head single cylinder vertical shaft air-cooled gasoline engine from GV-series. A 24.8 cu. in (406 cc) engine has a cylinder bore of 3.38" (86 mm), piston stroke of 2.76" (70 mm), and rated power of 11 Hp (8.2 kW) at 3600 rpm. The compression ratio rating is 6.5:1. The Honda GV400 engine is equipped with a trochoid oil pump lubrication, horizontal carburetor with butterfly valve, forced-air cooling system, and transistorized magneto ignition or CDI.

General Technical Data

Engine Specifications

Engine Model ................. Honda GV400
Engine Type ................. 4-cycle L-head 1-cylinder air-cooled small gasoline
Number of Cylinders ................. Single
Displacement, cu.in (cc) ................. 24.8 (406)
Cylinder Bore, in (mm) ................. 3.38 (86.0)
Piston Stroke, in (mm) ................. 2.76 (70.0)
Rated Engine Power, hp (kW) ................. 11.0 (8.2)
Rated Engine Speed, rpm ................. 3600
Maximum Torque, Nm (ft-lbs) ................. 24.5 (17.7)
Torque Speed, rpm ................. 3000
Compression Ratio ................. 6.5:1
Lubrication System ................. Trochoid oil pump
Cooling System ................. Forced air
Ignition System ................. Transistorized magneto or CDI
Starting System ................. Recoil or electric starter
Electrical System Rating, Volts .................. 12

Fuel System

Fuel System Type ................. Carburetor
Carburetor Type ................. Horizontal with butterfly valve
Fuel Consumption, g/HPh ................. 270
Fuel Type ................. Gasoline (86 or higher)
Fuel Tank Capacity, qts (L) ................. 2.4 (2.3)

Maintenance Data

Engine Oil

Engine Oil Type (Summer) ................. SAE 10W-30
Engine Oil Type (Winter) ................. SAE 10W
API Service Classifications ................. SG,SF/CC,CD
Oil Capacity, qts (L) ................. 1.25 (1.20)

Carburetor Adjustment

Carb Main Jet ................. #105
Float Height, in (mm) ................. 0.26-0.38 (6.7-9.7)
Pilot Screw Opening ................. 2-1/4 turns out
Low Idle Speed, rpm ................. 1700±150
High Idle Speed, rpm ................. 3850±150

Ignition System

Spark Plug Type (Magneto) ................. NGK BM6A, BMR6A
Spark Plug Type (CDI) ................. NGK BPM6A, BPMR6A
Spark Plug Gap (Magneto), in (mm) ................. 0.0236-0.0276 (0.60-0.70)
Spark Plug Gap (CDI), in (mm) ................. 0.035-0.039 (0.9-0.10)
Ignition Timing, deg ................. 20 BTDC
Spark Plug Torque, Nm (ft-lbs) ................. 20 (14.7)

Service Specifications

Cylinder Block

Cylinder Compression, psi (kPa) ................. 116 (800)
Cylinder Bore Inside Diameter (Std), in (mm) ................. 3.39 (86.00)
Cylinder Bore Inside Diameter (Wear Limit), in (mm) ................. 3.396 (86.10)
Connecting Rod Small End I.D (Std), in (mm) .................. 0.7482 (19.005)
Connecting Rod Small End I.D (Wear Limit), in (mm) .................. 0.7488 (19.020)
Crankpin Outside Diameter (Std), in (mm) .................. 1.46 (37.00)
Crankpin Outside Diameter (Wear Limit), in (mm) .................. 1.455 (36.951)
Piston Skirt Outside Diameter (Std), in (mm) ................. 3.385 (86.97)
Piston Skirt Outside Diameter (Wear Limit), in (mm) ................. 3.383 (85.85)
Top Ring Side Clearance, in (mm) .................. 0.0008-0.0024 (0.02-0.06)
Middle Ring Side Clearance, in (mm) .................. 0.0004-0.002 (0.01-0.05)
Oil Ring Side Clearance, in (mm) .................. 0.0004-0.002 (0.01-0.05)
Top Ring End Gap, in (mm) .................. 0.008-0.016 (0.20-0.40)
Middle Ring End Gap, in (mm) .................. 0.008-0.016 (0.20-0.40)
Oil Ring End Gap, in (mm) .................. 0.008-0.016 (0.20-0.40)

Cylinder Head and Valves

Cylinder Head (Max Out of Flatness), in (mm) ................. 0.004 (0.10)
Intake Valve Clearance, in (mm) ................. 0.002-0.005 (0.06-0.12)
Exhaust Valve Clearance, in (mm) ................. 0.004-0.006 (0.09-0.15)
Intake Valve Stem Outside Diameter, in (mm) ................. 0.2738-0.2744 (6.955-6.970)
Exhaust Valve Stem Outside Diameter, in (mm) ................. 0.2720-0.2726 (6.910-6.925)
Intake Valve Spring Free Length, in (mm) ................. 1.68 (42.7)
Exhaust Valve Spring Free Length, in (mm) ................. 1.68 (42.7)
Intake Cam Height, in (mm) ................. 1.516-1.524 (38.5-38.7)
Exhaust Cam Height, in (mm) ................. 1.516-1.524 (38.5-38.7)

Tightening Torque Specs

Cylinder Head Bolt, Nm (ft-lb) ................. 32-38 (23-27)
Connecting Rod Bolt, Nm (ft-lb) ................. 21-26 (15.6-19.1)
Flywheel Nut, Nm (ft-lb) ................. 110-120 (80-87)
Oil Drain Bolt, Nm (ft-lb) ................. 40-50 (29-36)
Fuel Tank Bolt, Nm (ft-lb) ................. 20-28 (15-20)
Oil Pan Bolt, Nm (ft-lb) ................. 21-26 (15.6-19.1)
Spark Plug, Nm (ft-lb) ................. 20 (14.7)

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• Honda Engines Specifications
  
• Honda G150 Specs
  
• Honda GV150 Specs
  
• Honda G200 Specs
  
• Honda GV200 Specs
  
• Honda G300 Specs
  
• Honda G400 Specs
  

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