Yamaha MOTO-4 1987 Owner's Manual page 90

MODEL YFMIOOT
Spark plug:
Type/manufacturer CR7HS/NGK
Gap 0.6 _ 0.7 mm (0.024 _ 0.028 in)
Clutch type: Wet, centrifugal automatic
Transmission:
Primary reduction system Spar gear
Primary reduction ratio 65/20 (3.250)
Secondary reduction system Shaft drive
Secondary reduction ratio 19/18 x 34/10 = 3.588
Transmission type Constant mesh, 4-speed forward
Operation Left foot operation
Gear ratio:
1st 39/11 (3.545)
2nd 35/17 (2.059)
3rd 31/22 (1.409)
4th 27/24 (1.125)
Chassis:
Frame type Steel t ube
Caster angle 1 °
Trail 3.8 mm (0.15 in)
10-3