The Honda NSR125 is a 2 stroke, 125 cc (lightweight) sport bike produced between 1988-2001. The high revving (red zone of the tachometer begins at 11,000 rpm), 2 stroke, RC-Valve equipped, single cylinder engine produced around Template:Convert/bhp at the crank. The name is taken from the NSR 500 GP bike which proved great success on the track.
History and Development
There were 2 models of the the NSR125; the earlier model, the JC20 consisted of the naked NSR125F with a square headlight and its the fully faired sister, the twin headlamp NSR125R, was produced between 1988-1994. The later "fox eye" model, the JC22, (named due to its front lights resembling that of a fox's eyes) was produced between 1993-2003.
Following the success of the NS125, the NSR125-JC20 was designed and assembled by Hondaitaria Indasutoriare in Rome, Italy. Grimeca was contracted to produce the Alcast frame (2-piece, die-cast, bolt together construction), wheels and brake assemblies. The engine was manufactured by Girardoni with Dellorto equipping the carberator. Marzocchi supplied forks and suspension while Pagani provided instrumentation and lighting. The NSR125-JC22 is mostly of Japanese manufacture, with the engine parts and other key elements of the running of the motorbike produced in Japan, It was then assembled in Italy and supplied to its mainly European market.
Although it is a common mistake to believe the NSR continued production until 2003. This is not the case as they ceased production in 2001 but had leftover stock until 2003/4.
Model Regional Differences
There is a large problem with de-restricting certain models of the NSR 125 and this is mainly dependent on where the bike was manufactured for. To tell the difference you must check your frame number. Which can be found on your documentaion for the bike.
This has the frame number ZDCJC22A
This is a full power bike and has no restrictions.
This has the frame number ZDCJC22C******
The restrictions on this bike are in the exhaust which must be drilled and filed out and a metal plate in the intake manifold which must be taken out.
Once both these things have been completed you must upjet the standard carburettor from 135 main, 65 power, 42 idle to a 138 main and you may leave the rest alone.
This has the frame number ZDCJC22B******
This is heavily restricted in both the exhaust, intake and also electrical restrictions. The exhaust restriction is about 8 inches in the exhaust and will require it to be cut open, removed and re-welded. A simple solution would be to buy a full power exhaust or a race exhaust.
The intake restriction is the same as all the others.
The electrical restrictions are in the CDI and come with a CI639 and TV-124. To fix this you will need to obtain the full power units CI626 and TV-78 from a UK or Italian spec bike.
Once this is completed you must change the jetting from the standard. 132main, 60 power and 40 idle to 138main, 65 power and 42 idle.
This has the frame number ZDCJC22E******
This has a load of restrictions and is nearly impossible to derestrict and cannot even rev past 7500 rpm.
This has the frame number HI-JC20[star]1****[star]
This has a 26mm carb instead of the JC22s 28mm and an air intake restriction. 22 kilowatts is maximum power output.
Specifications for the Honda NSR125 that are manufacture claimed or estimated.
Engine and Transmission
- Displacement: 124.00 cc
- Engine type: 2 cycle, single cylinder
- Torque: 1,98 Kpm/9000 rpm (unrestricted)
- Power: 29 hp/10250 rpm (unrestricted)
- Bore x stroke: 54.0 x 54.5 mm
- Gearbox: 6-speed
- Transmission type final drive: Chain
- Tank volume: 13 litres (incl. reserve)
- Dry weight: 132.0 kg
- Seat height: 800 mm
- Overall length: 2,075 mm
- Overall width: 670 mm
Chassis and Dimensions
- Chassis: Die-cast aluminium
- Front tyre dimensions: 100/80-17
- Rear tyre dimensions: 130/70-17
- Front brakes: Single disc with 2 piston Grimeca callipers
- Rear brakes: Single disc with 1 piston Grimeca callipers
- 125cc Sports Bikes Forum NSR125 section
- NSR reference site
- NSR125 Exhaust Sound Recording
- NSR125R Forum and Help Website
- NSR125F Press Release
Honda motorcycle timeline, 1990s–present
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