1. Deburr: valve stem end (with an oil stone)
2. Lubricate:
- valve stem
- oil seal: New (with the recommended lubricant)
Recommended lubricant: Molybdenum disulfide oil
3. Install:
- valve
- lower spring seat
- oil seal: New
- valve spring
- upper spring seat (into the cylinder head)
Note: Install the valve spring with the larger pitch (a) facing up.
![](https://motoinstruction.ru/img/yamaha/16/122306.jpg)
(b) Smaller pitch
4. Install: valve cotters
Note: Install the valve cotters by compressing the valve spring with the valve spring compressor (1).
![](https://motoinstruction.ru/img/yamaha/16/122307.jpg)
- Valve spring compressor: 90890-04019
5. To secure the valve cotters onto the valve stem, lightly tap the valve tip with a soft-face hammer.
![](https://motoinstruction.ru/img/yamaha/16/122308.jpg)
Caution! Hitting the valve tip with excessive force could damage the valve.