Yamaha YZ125X 2023, Owner'S Manual

Page: 33 / 146

ENGINE SPECIFICATIONS
2-2
EAM20128
ENGINE SPECIFICATIONS
Engine
Combustion cycle 2-stroke
Cooling system Liquid cooled
Induction system Reed valve
Displacement 125 cm³
Number of cylinders Single cylinder
Bore

stroke 54.0

54.5 mm (2.13

2.15 in)
Compression ratio 7.8–10.2 : 1
Starting system Kickstarter
Fuel
Recommended fuel Premium unleaded gasoline (E10 acceptable)
Fuel tank capacity 7.0 L (1.8 US gal, 1.5 Imp.gal)
Fuel reserve amount 2.0 L (0.53 US gal, 0.44 Imp.gal)
Engine oil
Recommended brand YAMALUBE
Lubrication system Premix lubrication
Engine oil YAMALUBE 2R
Premix ratio 30
Transmission oil
Type Motor oil SAE 10W-40 type SG or higher
Quantity (disassembled) 0.76 L (0.80 US qt, 0.67 Imp.qt)
Quantity 0.70 L (0.74 US qt, 0.62 Imp.qt)
Cooling system
Coolant quantity
Radiator (including all routes) 0.90 L (0.95 US qt, 0.79 Imp.qt)
Spark plug(s)
Manufacturer/model NGK/BR9EVX
Spark plug gap 0.6–0.7 mm (0.024–0.028 in)
Clutch
Clutch type Wet, multiple-disc
Clutch lever free play 7.0–12.0 mm (0.28–0.47 in)
Friction plate thickness 2.90–3.10 mm (0.114–0.122 in)
Wear limit 2.80 mm (0.110 in)
Plate quantity 8 pcs
Clutch plate thickness 1.50–1.70 mm (0.059–0.067 in)
Plate quantity 7 pcs
Warpage limit 0.20 mm (0.008 in)
Clutch spring free length 41.20 mm (1.62 in)
Clutch spring free length limit 39.20 mm (1.54 in)
Push rod bending limit 0.30 mm (0.012 in)
Drivetrain
Primary reduction ratio 3.368 (64/19)
Transmission type Constant mesh 6-speed
Gear ratio
1st 2.385 (31/13)
2nd 1.933 (29/15)
3rd 1.588 (27/17)