Yamaha YZ125 2021 Owner's Service Manual page 42

Crankshaft
Crank assembly width
Runout limit
Clutch
Clutch type
Clutch lever free play
Friction plate thickness
Wear limit
Plate quantity
Clutch plate thickness
Plate quantity
Warpage limit
Clutch spring free length
Clutch spring free length limit
Push rod bending limit
Drivetrain
Primary reduction ratio
Transmission type
Gear ratio
1st
2nd
3rd
4th
5th
6th
Main axle runout limit
Drive axle runout limit
Secondary reduction ratio
Final drive
Air filter
Air filter element
Air filter oil grade
Carburetor
Type  quantity
ID mark
Main jet
Main air jet
Jet needle
Needle jet
Cutaway
Pilot outlet
Pilot jet
Bypass 1
Bypass 2
Air screw turns out
Valve seat size
Starter jet 1
Fuel level (using fuel level gauge)
Throttle grip free play
ENGINE SPECIFICATIONS
55.90–55.95 mm (2.201–2.203 in)
0.050 mm (0.0020 in)
Wet, multiple-disc
7.0–12.0 mm (0.28–0.47 in)
2.90–3.10 mm (0.114–0.122 in)
2.80 mm (0.110 in)
8 pcs
1.50–1.70 mm (0.059–0.067 in)
7 pcs
0.20 mm (0.008 in)
40.10 mm (1.58 in)
38.10 mm (1.50 in)
0.30 mm (0.012 in)
3.368 (64/19)
Constant mesh 6-speed
2.385 (31/13)
1.933 (29/15)
1.588 (27/17)
1.353 (23/17)
1.200 (24/20)
1.095 (23/21)
0.01 mm (0.0004 in)
0.01 mm (0.0004 in)
3.692 (48/13)
Chain
Wet element
Yamaha foam air filter oil or other quality foam
air filter oil
TMXx38  1
1C37 51
#430
2.5
6BFY43-74-3
S-1
4
0.7
#40
0.7
0.7
2-1/4
3.8
#80
9.5–10.5 mm (0.37–0.41 in)
3.0–5.0 mm (0.12–0.20 in)
2-3