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.
|Model Name||TL 125 S|
|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)|
|Valves per Cylinder||2|
|Curb Weight||106 kg (234 lb)|
|Fuel Capacity||4.5 litres (1.19 gallons)|
|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|
Identifying Various Year Models of the TL125
|Model||Year||Serial no||Petrol tank
|TL125 (K)||1973||Frame TL125-1000003 onwards
Engine TL125E-1000001 onwards
|TL125 K1||1974||Frame TL125-1100001 onwards
Engine TL125E-1100001 onwards
Candy Sapphire Blue
|TL125 K2||1975||Frame TL125-1200001 onwards
Engine TL125E-1200001 onwards
|TL125S 76||1976||Frame TL125S-1000417 onwards
Engine TL125S-1000001 onwards
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.|
|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.|
|NGK D8ES-L||ND X24ES|
|10.8 – 13.2 kg/cm2||156 – 187 psi|
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.
12, 13, 14, 16, 17, 18, 19 also available
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|
|Main jet: 92||Part #99101-116-0920, Honda code 0426072|
|Idle jet: 35||Part #99103-355-0350, Honda code 0426080|