1. Measure:
- Valve spring free length "a"
Out of specification → Replace the valve spring.
Valve spring free length. Free length (intake) 39.33 mm (1.55 in).
Limit 37.3 6 mm (1.47 in).
Free length (exhaust) 37.9 6 mm (1.49 in).
Limit 36.06 mm (1.42 in).
![](https://motoinstruction.ru/img/yamaha/20/126653.jpg)
2. Measure:
- Compressed valve spring force "a". Out of specification → Replace the valve spring.
Installed compression spring force (intake) 187.00-215.00 N (19.07-21.92 kgf, 42.04-48.33 Ibf).
Installed compression spring force (exhaust) 185.00-213.00 N (18.86-21.72 kgf, 41.59-47.88 lbf).
Installed length (intake) 34.50 mm (1.36 in).
Installed length (exhaust) 33.00 mm (1.30 in).
![](https://motoinstruction.ru/img/yamaha/20/126654.jpg)
b. Installed length
3. Measure:
- Valve spring tilt "a"
Out of specification → Replace the valve spring.
Spring tilt limit:
Spring tilt (intake) 2.5°/1.7 mm (0.067 in).
Spring tilt (exhaust) 2.5°/1.7 mm (0.067 in).
![](https://motoinstruction.ru/img/yamaha/20/126655.jpg)