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Yamaha YZ125

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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 number of well known riders have chosen this as their go-to bike, such as AMA Champ Dom Barbuto and his brother Nick Barbuto, X-Games medalist Kyle Ford, and StinkBike Racing's own local Seattle legend Joey Merkin. Also, 11-time Nationals winner and rival of Eli Tomac, Richard Rich

References

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  1. ^ a b "Two-Stroke Shootout: KTM 125SX Vs. YAMAHA YZ25". Motocross Action Magazine. 19 November 2016. Retrieved 6 May 2019.
  2. ^ a b 2010 YZ125 Specs, Yamaha Motor Corporation, USA, archived from the original on 2009-11-25, retrieved 2009-12-05
  3. ^ "MXA's 20 Most Frequently Asked Questions". MotoCross Action Magazine. Archived from the original on 27 February 2010. Retrieved 6 May 2019.
  4. ^ "EVERY CHAMP | Motocross Action". Archived from the original on 2012-09-05. Retrieved 2007-05-09.
  5. ^ "10 Things You Might Not Know About The YZ125". Dirt Bike Magazine. Retrieved 6 May 2019.
  6. ^ "2016 YAMAHA YZ125 Two-Stroke Race Test: Everything You Need To Know". MotoCross Action Magazine. 18 April 2016. Retrieved 6 May 2019.
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