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2020 Yamaha YZ125 Overview
Yamaha YZ125 is a cross / motocross motorcycle, displacing 125 cc. Power comes from a Single cylinder, two-stroke engine, a compression ratio of 10.7:1. Bore and stroke come in at 54 x 54.5 mm. On the road, the 2020 YZ125 tips the scales at 93.9 kg, carries a 8-litre fuel tank, offers a seat height of 975 mm and spans a 1443 mm wheelbase. The full 2020 Yamaha YZ125 spec sheet below covers every technical detail, from suspension travel to tyre sizes.
2020 YZ125 - Pros & Cons
Strengths
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Factory engineering: Yamaha built the YZ125 around a straightforward, purposeful specification rather than chasing any single standout feature.
Considerations
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🔧
Carburetor fuelling: Expect to spend more time keeping the carbs in tune, especially after long storage periods or a change in altitude.
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📏
Tall seat height: At 975 mm, shorter riders will likely be on tiptoes at a standstill - worth sitting on one before you buy.
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Modest fuel capacity: Range between stops is limited by the 8-litre tank - plan fuel stops accordingly on longer routes.
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Chain final drive upkeep: Budget time for routine chain maintenance - it's cheap to replace but needs consistent attention to avoid premature sprocket wear.
Wear Points & Servicing Notes
Carburetor maintenance
Carburetors on the YZ125 need periodic attention - pilot jets and float needles are the first parts to gum up after the bike sits, and the first thing to check if idle or throttle response degrades.
Brake disc and pad wear
Braking up front comes from Single disc. Hydraulic. - solid stopping power, with disc and pad wear best checked on the same schedule as tyre changes.
Suspension condition on used examples
The YZ125's suspension runs KYB® Speed-Sensitive System inverted fork; fully adjustable at the front. The rear uses KYB® single shock; fully adjustable. Fork-seal condition and rear linkage play are the two things worth checking before buying used.
Final drive maintenance
The YZ125 uses chain final drive, which is cheap to replace but needs regular cleaning, lubrication and tension checks to get a full service life out of the sprockets.
Frame & chassis check
Built around a Semi-double cradle aluminium frame, the YZ125's chassis is straightforward to inspect: look for corrosion, cracks or repair welds around stress points like the head-stock and swingarm mounts.
Low-speed handling
93.9 kg keeps the YZ125 easy to move around in tight spaces, car parks and on the stand alike.
YZ125 - Buying & Maintenance Guide
What to check before buying
Before handing over money for a used 2020 Yamaha YZ125, cover the fundamentals: service book and oil change history, chain and sprocket wear, and any sign of oil weeping around the casings. Cold-starting it yourself tells you a lot - a healthy YZ125 should catch quickly and settle into a smooth idle.
Oil and filter changes
Nothing protects a YZ125's engine like disciplined oil changes - stay on the manufacturer's schedule (roughly every 6,000 km or annually). The sump holds 0.70 litres, so budget for that volume of quality motorcycle-specific engine oil. Match the viscosity grade to what the owner's manual specifies, not what's cheapest.
Carburetor upkeep
Deposits in the carbs are the usual culprit behind poor running on a stored YZ125 - strip and clean the float bowls before the first start. Pilot jets clog first and get overlooked most, so make a point of checking them.
2020 Yamaha YZ125 - Frequently Asked Questions
What engine does the 2020 Yamaha YZ125 have?
The 2020 Yamaha YZ125 uses a Single cylinder, two-stroke engine with 125 cc of displacement.
How much does the 2020 Yamaha YZ125 weigh?
The 2020 Yamaha YZ125 weighs 93.9 kg. This is the manufacturer's wet figure.
What is the fuel tank capacity of the 2020 Yamaha YZ125?
The 2020 Yamaha YZ125 has a 8-litre fuel tank. At around 5-6 litres per 100 km, that is roughly 133-160 km between stops.
Is the 2020 Yamaha YZ125 suitable for shorter riders?
The 2020 Yamaha YZ125 has a seat height of 975 mm. This is towards the tall end of the spectrum and will require most riders under 175 cm to tiptoe at stops.
What brakes does the 2020 Yamaha YZ125 have?
The 2020 Yamaha YZ125 uses Single disc. Hydraulic. at the front and Single disc. Hydraulic. at the rear.
What tyre sizes does the 2020 Yamaha YZ125 use?
The front tyre size on the 2020 Yamaha YZ125 is 80/100-21.
How much oil does the 2020 Yamaha YZ125 take?
The 2020 Yamaha YZ125 takes 0.70 litres of engine oil at a full oil and filter change. Always verify against the dipstick or sight glass after filling.
Yamaha YZ125 Spec Evolution
The Yamaha YZ125 was produced across 21 model years (2002-2023). The table below highlights the key specifications that changed across the production run - useful whether you are comparing years or tracking down a specific variant.
| Specification |
2002 |
2004 |
2005 |
2006 |
2007 |
2008 |
2009 |
2010 |
2011 |
2012 |
2013 |
2014 |
2015 |
2016 |
2017 |
2018 |
2019 |
2020 |
2021 |
2022 |
2023 |
| Wet Weight |
- |
- |
- |
- |
- |
- |
94.3 kg / 208.0 lbs |
94.3 kg / 208.0 lbs |
94.4 kg / 208.0 lbs |
94.4 kg / 208.0 lbs |
93.9 kg / 207.0 lbs |
93.9 kg / 207.0 lbs |
94.8 kg / 209.0 lbs |
94.8 kg / 209.0 lbs |
94.8 kg / 209.0 lbs |
93.9 kg / 207.0 lbs |
93.9 kg / 207.0 lbs |
93.9 kg / 207.0 lbs |
93.9 kg / 207.0 lbs |
94.8 kg / 209.0 lbs |
94.8 kg / 209.0 lbs |
| Dry Weight |
87.5 kg / 192.9 lbs |
87 kg / 191.8 lbs |
- |
86 kg / 189.6 lbs |
86.2 kg / 190.0 lbs |
86.2 kg / 190.0 lbs |
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- |
- |
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210.5 kg / 464.1 lbs |
59 kg / 130.1 lbs |
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- |
- |
- |
- |
- |
- |
- |
- |
| Engine Detail |
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- |
- |
- |
- |
- |
- |
- |
- |
Reed-valve inducted |
Reed-valve-inducted |
Reed-valve-inducted |
Reed-valve-inducted |
Reed-valve-inducted |
Reed-valve-inducted |
Reed-valve-inducted |
Reed-valve-inducted |
Reed-valve-inducted |
Reed-valve-inducted |
Reed-valve-inducted |
Reed-valve-inducted |
| Engine Type |
Single cylinder |
Single cylinder |
Single cylinder |
V2 |
Single cylinder |
Single cylinder |
Single cylinder |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
Single cylinder, two-stroke |
| Top Speed |
- |
- |
- |
- |
- |
- |
- |
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- |
- |
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120.0 km/h / 74.6 mph |
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- |
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96.0 km/h / 59.7 mph |
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- |
- |
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| Seat Height |
994 mm / 39.1 in. |
992 mm / 39.1 in. |
993 mm / 39.1 in. |
998 mm / 39.3 in. |
998 mm / 39.3 in. |
998 mm / 39.3 in. |
998 mm / 39.3 in. |
998 mm / 39.3 in. |
998 mm / 39.3 in. |
998 mm / 39.3 in. |
998 mm / 39.3 in. |
998 mm / 39.3 in. |
975 mm / 38.4 in. |
975 mm / 38.4 in. |
975 mm / 38.4 in. |
975 mm / 38.4 in. |
975 mm / 38.4 in. |
975 mm / 38.4 in. |
975 mm / 38.4 in. |
39 mm / 1.5 in. |
980 mm / 38.6 in. |
| Fuel Capacity |
- |
- |
7.94 litres / 2.10 gallons |
8.00 litres / 2.11 gallons |
7.94 litres / 2.10 gallons |
7.94 litres / 2.10 gallons |
7.94 litres / 2.10 gallons |
7.94 litres / 2.10 gallons |
7.95 litres / 2.10 gallons |
7.95 litres / 2.10 gallons |
7.95 litres / 2.10 gallons |
7.95 litres / 2.10 gallons |
7.95 litres / 2.10 gallons |
7.95 litres / 2.10 gallons |
8.00 litres / 2.11 gallons |
8.00 litres / 2.11 gallons |
8.00 litres / 2.11 US gallons |
8.00 litres / 2.11 US gallons |
8.00 litres / 2.11 US gallons |
6.81 litres / 1.80 US gallons |
6.81 litres / 1.80 US gallons |
| Oil Capacity (Quarts) |
- |
- |
- |
- |
- |
- |
- |
- |
0.05 quarts |
- |
- |
- |
- |
- |
0.05 quarts |
0.05 quarts |
0.74 US quarts |
0.74 US quarts |
0.74 US quarts |
0.74 US quarts |
0.74 US quarts |
Key Specifications
Engine
Single cylinder, two-stroke
Power
Not published by manufacturer
Torque
Not published by manufacturer
Top Speed
Not published by manufacturer
Weight
93.9 kg / 207.0 lbs
Fuel Capacity
8.00 litres / 2.11 US gallons
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Full 2020 Yamaha YZ125 Specifications
Colours
Team Yamaha Blue
Warranty
30 Day Limited Factory Warranty
Ground Clearance (in.)
14.4 inches
Ground Clearance (mm)
366 mm
Seat Height
975 mm / 38.4 in.
Wheelbase
1443 mm / 56.8 in.
Height
1295 mm / 51.0 in.
Length
2136 mm / 84.1 in.
Width
828 mm / 32.6 in.
Oil Capacity (l)
0.70 litres
Oil Capacity (Quarts)
0.74 US quarts
Fuel Capacity
8.00 litres / 2.11 US gallons
Wet Weight
93.9 kg / 207.0 lbs
Bore x Stroke (in,)
2.1 x 2.1 inches
Bore x Stroke (mm)
54.0 x 54.5 mm
Displacement (cc)
125.0 cc
Displacement (ci)
7.63 cubic inches
Engine Type
Single cylinder, two-stroke
Engine Detail
Reed-valve-inducted
Fuel System
Carburettor. Mikuni TMX 38
Compression Ratio
10.7:1
Engine Lubrication
Premix
Ignition
CDI
Starter
Kick
Clutch
Multiplate wet clutch
Final Drive
Chain (final drive)
Gearbox
6-speed
Frame Type
Semi-double cradle aluminium frame
Suspension - Front
KYB® Speed-Sensitive System inverted fork; fully adjustable
Suspension - Rear
KYB® single shock; fully adjustable
Rake
26.0°
Trail
109 mm / 4.3 in.
Wheel Travel - Front
300 mm / 11.8 in.
Wheel Travel - Rear
315 mm / 12.4 in.
Brakes - Front
Single disc. Hydraulic.
Brakes - Rear
Single disc. Hydraulic.
Rims
Dunlop® MX52
Tyres - Front
80/100-21
Specifications are compiled from manufacturer documentation and cross-referenced
technical sources, and corrected on an ongoing basis.
Spot an error? Let us know.
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