Yamaha YZ 2018 Series, Owner'S Service Manual, Page: 45 / 402

ENGINE SPECIFICATIONS
2-4
Piston ring
Top ring
Ring type Barrel
End gap (installed) 0.15–0.25 mm (0.0059–0.0098 in)
End gap limit 0.50 mm (0.0197 in)
Ring side clearance 0.030–0.065 mm (0.0012–0.0026 in)
Side clearance limit 0.115 mm (0.0045 in)
Crankshaft
Crank assembly width 55.93–56.00 mm (2.202–2.205 in)
Runout limit 0.030 mm (0.0012 in)
Clutch
Clutch type Wet, multiple-disc
Clutch lever free play 7.0–12.0 mm (0.28–0.47 in)
Friction plate 1 thickness 2.90–3.10 mm (0.114–0.122 in)
Wear limit 2.85 mm (0.112 in)
Plate quantity 4 pcs
Friction plate 2 thickness 2.90–3.10 mm (0.114–0.122 in)
Wear limit 2.85 mm (0.112 in)
Plate quantity 5 pcs
Clutch plate thickness 1.10–1.30 mm (0.043–0.051 in)
Plate quantity 8 pcs
Warpage limit 0.10 mm (0.004 in)
Clutch spring free length 47.80 mm (1.88 in)
Limit 45.41 mm (1.79 in)
Spring quantity 5 pcs
Push rod bending limit 0.30 mm (0.012 in)
Drivetrain
Primary reduction ratio 3.353 (57/17)
Transmission type Constant mesh 6-speed
Gear ratio
1st 2.385 (31/13)
2nd 1.813 (29/16)
3rd 1.444 (26/18)
4th 1.143 (24/21)
5th 0.957 (22/23)
6th 0.815 (22/27)
Main axle runout limit 0.08 mm (0.0032 in)
Drive axle runout limit 0.08 mm (0.0032 in)
Secondary reduction ratio 3.923 (51/13)
Final drive Chain
Air filter
Air filter element Wet element
Air filter oil grade Yamaha foam air filter oil or other quality foam
air filter oil
Fuel pump
Pump type Electrical
Fuel injector
Resistance 12.0
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