Technical & consumer information 59 – HONDA HHT31S User Manual
Page 61
TECHNICAL & CONSUMER INFORMATION
59
Tuneup
ENGINE
HHT25S
HHT31S
Model
GX25
GX31
Engine type
4-stroke, overhead-cam, single-cylinder
4-stroke, overhead-valve, single-cylinder
Displacement
1.5 cu in (25 cc)
1.9 cu in (31 cc)
Bore & stroke
1.4 x 1.0 in (35 x 26 mm)
1.5 x 1.0 in (39 x 26 mm)
Maximum output
1.1 hp (0.82 kW) at 7,000 rpm
1.5 hp (1.1 kW) at 7,000 rpm
Maximum torque
0.8 ft-lbs (1.09 N
•
m) at 5,000 rpm
1.23 ft-lbs (1.64 N
•
m) at 4,500 rpm
Ignition system
Transistorized magneto
Spark plugs
NGK: CMR5H
NGK: CR5HSB or DENSO: U16FSR-UB
Starting system
Recoil
Fuel
Unleaded gasoline (86 octane or higher)
Fuel tank capacity
0.53 qt/16.9 fl.oz (0.50
)
0.69 qt/22.0 fl oz (0.65
)
Fuel consumption
0.61 lb/hph (370 g/kWh, 276 g/psh)
0.55 lb/hph (340 g/kWh, 250 g/psh)
Oil capacity
2.7 fl oz (80 cc)
3.4 fl oz (100 cc)
Carburetor type
Diaphragm type (overflow return) with fuel pump
Air cleaner
Single element, semi-dry
Idle speed
3,100 ± 200 rpm
FRAME
HHT25S
HHT31S
Ignition switch
Slide type
Throttle control
Two-motion trigger style
Frame pipe
OD
1.0 in (25.4 mm)
Thickness
0.059 in (1.5 mm)
Drive
Type
Material
Flexible steel cable
OD
0.25 in (6.3 mm)
Engagement
0.20 in (5 mm) square drive both ends
Bushing
Material
Nylon
Length
57-1/2 inch (1460 mm)
Gear case
Ratio
1.24 (input shaft) : 1 (output shaft)
Type
Ball bearings, helical cut gears, no shims required
Clutch
Size
2-1/8 inch
3-1/16 inch
Engagement
4,200 ± 200 rpm
Drive
Square female
Type
Centrifugal
ITEM
SPECIFICATION
MAINTENANCE
Spark plug gap
0.024 - 0.028 in
(0.60 - 0.70 mm)
Valve clearance
(cold)
HHT25S
Intake: 0.08 ± 0.02 mm
Exhaust: 0.11 ± 0.02 mm
See your authorized
servicing Honda dealer
HHT31S
Intake: 0.12 ± 0.02 mm
Exhaust: 0.15 ± 0.02 mm