Specifications

Honda Started manufacture of the TL125 in 1972, and was known in Japan as the ‘BIALS’. The engine at the time was a 122cc unit two valve SOHC from the SL125.

 

In 1973, the TL125 and TL250 went into full production for the US, Japan and European markets.

 

The machine was a worldwide model and had various modifications or improvements to suit each particular home market where it was being sold.

TECHNICAL SPECIFICATION

TECHNICAL SPECIFICATION
Model ID
Manufacturer (Make) Honda
Model Name TL 125 S
Year 1977
Category(class) Trial
Engine
Engine Capacity (Displacement) 124 ccm (7.57 cubic inches)
Engine Type 1 cylinder
Bore x Stroke Ø56.5 mm x 49.5 mm (Ø2.22 inches x 1.95 inches)
Bore/Stroke Ratio 1.14
Stroke 4
Valves per Cylinder 2
Timing System OHC
Cooling System Air
Powertrain
Gearbox 5 speed
Chassis/Suspension/Brakes
Front Brakes Drum
Rear Brakes Drum
Front Tire 2.75-21
Rear Tire 4.00-18
Dimensions
Curb Weight 106 kg (234 lb)
Fuel Capacity 4.5 litres (1.19 gallons)
Performance
Max Power 9.00 HP (6.6 kW) at 8750 RPM
Power/Weight Ratio 0.08 Hp/Kg
Top Speed 90 km/h (56mph)
Acceleration (dart, speedup) time
0-100 km/h 20.2 seconds
0-60 mph 19.2 seconds
  • 1/4 mile
  • 60 to 140 km/h, highest gear

Identifying Various Year Models of the TL125

Model Year Serial no Petrol tank
accent color
TL125 (K) 1973 Frame TL125-1000003 onwards
Engine TL125E-1000001 onwards
Tahitian Red
TL125 K1 1974 Frame TL125-1100001 onwards
Engine TL125E-1100001 onwards
Tahitian Red
Candy Sapphire Blue
TL125 K2 1975 Frame TL125-1200001 onwards
Engine TL125E-1200001 onwards
Tahitian Red
TL125S 76 1976 Frame TL125S-1000417 onwards
Engine TL125S-1000001 onwards
Shiny Orange

 

Generally the TL125 engines can be divided into one-piece-head (1973 to 1975) and two-piece-head (1976). In the latter the cylinder head breaks horizontally into two, camshaft in between.

Main Differences Between Year Models

Model Year Main Difference to Previous Year
TL125 1973 First production year
TL125 K1 1974 Pretty much the same as 1973, some minor differences.
Right engine cover slightly different (carries different Hoda part number).
TL125 K2 1975 New front forks (Showa).
TL125S 76 1976 Two piece head, 0.5mm larger bore diameter.

Engine General

Year Bore & Stroke Displacement CR HP
1973 – 1975 56.0mm x 49.5mm 122cc 8:1 8 @ 8000 rpm
1976 56.5mm x 49.5mm 124cc 8:1 8 @ 8000 rpm

Some TL125 Tune-up Information

Engine oil capacity
1.0 liters 1.0 U.S. qt.
Front fork oil capacity (reassembly)
130 – 140 cc 4.4 – 4.7 fl. oz.
Valve clearance (I&E)
0.05 mm 0.002 in.
Spark plug
NGK D8ES-L ND X24ES
Compression
10.8 – 13.2 kg/cm2 156 – 187 psi

Gear Ratios

In TL125 the 1st, 2nd and 3rd are very low and close for off road work, 5th is as long as could be accommodated in the space available and 4th just bridges the gap.

CG/CB100 TL125 XL185 TL125
Overall
Primary 4.055 4.055 3.333
1st 2.769 2.769 2.769 44.91
2nd 1.882 2.125 1.722 34.46
3rd 1.450 1.450 1.272 25.59
4th 1.173 1.000 1.000 16.22
5th 1.000 0.724 0.777 11.74

Final Drive
Front 15 teeth
12, 13, 14, 16, 17, 18, 19 also available
Rear 60 teeth
40, 49, 52 also available
Chain 428 – 120L

Carburetor and Jetting

All TLs have a 20mm Keihin roundslide carburetor (18mm slide). Jetting is slightly leaner on the 1976 S model.

1973 to 1975 TL125
Main jet: 95 Part #99114-246-0950, Honda code 0173336
Idle jet: 38 Part #99124-089-0380, Honda code 0185884
1976 TL125S
Main jet: 92 Part #99101-116-0920, Honda code 0426072
Idle jet: 35 Part #99103-355-0350, Honda code 0426080
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