The Honda CB125s is a 122 cc motorcycle manufactured by Honda from 1971-1975 (1973-1985 in the US). It features an overhead camshaft (OHC) engine with a 9500 rpm redline and offers 100 mpg, quite astonishing for its period. It could comfortably maintain speeds of 55 mph and had a top speed of around 65 mph. Its low weight coupled with the free revving engine allowed it to surpass many bigger, more unreliable British bikes in performance. The engine could last tens of thousands of miles with only minimal attention; however, the oil had to be changed regularly (700 miles) to prevent premature wear of the camshaft bearings. The "S" model was produced from 1971 to 1975 and was replaced in 1976 by the "J" model (the US bikes retained the S designation). The newer model sported a two piece head, 124cc displacement, and a larger carburettor, but it did not perform as well as the earlier models.
- Displacement: 122 cc (7.63 cubic inches)
- Engine Type: Single Cylinder
- Stroke: 4
- Power: 12.00 HP @ 9000 rpm
- Torque: 7.28 lb.ft @ 8000 rpm
- Compression: 9.4:1
- Bore x Stroke: 56.0 x 49.5 mm (2.2 x 1.9 inches)
- Valves Per Cylinder: 2
- Fuel Control: OHC
- Wet Weight: 220 lbs
- Cooling System: Air
- Gearbox: 5-speed Wet Sump
- Drive Train: Chain
- Top Speed : 65 mph
- Fuel Economy : 100 mpg
Major Changes Throughout The Years
Aside from different color schemes and minor lettering differences, these are some of the major design changes that this bike went through.
- 1973 - First year the bike was released in the US (CB125S0).
- 1974 - Front drum brake changed to (poorly designed) mechanical disk, tachometer was added.
- 1976 - Engine displacement increased from 122 to 124cc, tachometer was eliminated.
- 1979 - Front disk brake was changed back to drum.
- 1980 - Point ignition was changed to capacitive discharge.
- 1983 - The bike was not produced this year.
- 1984 - The electrical system was changed from 6 to 12 volts.
- 1985 - The last year the bike was released in the US, headlight shape was changed from round to rectangular.