Engineering:Yamaha YZ125

From HandWiki
YZ125
ManufacturerYamaha
ProductionSince 1974
ClassMotocross
Engine124 cc (7.6 cu in) reed valve two-stroke single
Power33.53 hp (25.00 kW)[1]
Transmission5- or 6-speed sequential manual
SuspensionMono-shock, 13 inches travel
BrakesHydraulic disc
TiresFront: 80/100-21-51M
Rear: 100/90-19-57M
Wheelbase1,440 mm (56.8 in)
DimensionsL: 2,140 mm (84.1 in)
W: 830 mm (32.6 in)
H: 1,320 mm (51.8 in)
Seat height1,000 mm (39.3 in)
Weight86 kg (190 lb) (dry)
94 kg (208 lb)[2] (wet)
Fuel capacity7.9 l; 1.7 imp gal (2.1 US gal)
RelatedYamaha YZ250F

The Yamaha YZ125 is a motocross racing motorcycle with a two-stroke 124.9 cc (7.62 cu in) displacement single-cylinder engine made by Yamaha since 1974. It is available to the public. For the first two years it was made with dual rear shocks, then changing to a monoshock.[3] The YZ125 has been ridden to five AMA National Motocross Championships, and multiple AMA Regional Supercross Championships.[4]

In 2001, Yamaha released a bike designed to complement the YZ125, the four-stroke YZ250F. The two bikes shared a rolling chassis and are eligible to compete in the same racing class. The YZ250F has a slight horsepower advantage.[5]


The YZ125 has a 124 cc (7.6 cu in) reed valve-inducted two-stroke engine. It was air cooled from 1974 to 1980, and liquid cooled since 1981. It has a Mikuni 38 mm TMX series carburetor.[6] The engine produces 35 hp (26 kW).[1]

The YZ125 has been built with five- or six-speed manual sequential gearbox depending on model year. The 2005 model has a constant-mesh, wet, multiple-disc coil-spring clutch.


From 1973 through 2004, the YZ125 had a single backbone frame made from steel. It generally averaged from 176 to 198 lb (80 to 90 kg).[citation needed] For the 2005 year, Yamaha switched to a single backbone frame constructed from an aluminum alloy. This frame material change dropped the dry weight to 190 lb (86 kg).[citation needed] For 2008 models, the wheel assemblies and front fork suspension were redesigned, yielding additional weight savings, making wet weight, no gas sub-200 lb. Aluminum-framed YZ125s are notably "flickable" and sometimes this trait is seen as a drawback since they tend to become more difficult to control on rough surfaces.[2] The YZ125 used a conventional telescopic fork tube through 1988, then in 1989, added the first upside-down fork. A very well knows the amount of riders have chosen this as their go-to bike, such as AMA Champ Dom Barbuto and his brother Nick Barbuto, and X-Games medalist Kyle Ford. Also, 11-time Nationals winner and rival of Eli Tomac, Richard Rich

References

External links