Yamaha YZ 2020 Series, Owner'S Service Manual

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ENGINE SPECIFICATIONS
2-4
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 2.70–2.90 mm (0.106–0.114 in)
Wear limit 2.60 mm (0.102 in)
Plate quantity 2 pcs
Friction plate 2 thickness 2.72–2.88 mm (0.107–0.113 in)
Wear limit 2.62 mm (0.103 in)
Plate quantity 6 pcs
Clutch plate thickness 1.50–1.70 mm (0.059–0.067 in)
Plate quantity 7 pcs
Warpage limit 0.10 mm (0.004 in)
Clutch spring free length 44.00 mm (1.73 in)
Limit 41.80 mm (1.65 in)
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
Maximum consumption amperage 2.4 A
Fuel injector
Resistance 12.0

Throttle body
ID mark B7B1 00
Idling condition
Engine idling speed 1900–2100 r/min
Coolant temperature 70–80

C (158–176

F)
Fuel line pressure (at idle) 300–390 kPa (3.0–3.9 kgf/cm², 43.5–56.6 psi)