- Piston pin
Blue discoloration/grooves → Replace the piston pin and then check the lubrication system.
2. Measure:
- Piston pin outside diameter "a"
Out of specification → Replace the piston pin.
Piston pin outside diameter 16.991-17.000 mm (0.6689-0.6693 in).
Limit 16.971 mm (0.6682 in).
![](https://motoinstruction.ru/img/yamaha/20/126756.jpg)
3. Measure:
- Piston pin bore inside diameter "b". Out of specification → Replace the piston.
- Piston pin bore inside diameter 17.002-17.013 mm (0.6694-0.6698 in).
Limit 17.043 mm (0.6710 in).
![](https://motoinstruction.ru/img/yamaha/20/126757.jpg)
4. Calculate:
- Piston-pin-to-piston-pin-bore clearance. Out of specification → Replace the piston pin and piston as a set.
- Piston-pin-to-piston-pin-bore clearance = Piston pin bore inside diameter "b" - Piston pin outside diameter "a"
- Piston-pin-to-piston-pin-bore clearance 0.002-0.022 mm (0.0001- 0.0009 in). Limit 0.072 mm (0.0028 in)