Remove the two bolts of the forks.
![](https://motoinstruction.ru/img/aprilia/17/122959.jpg)
![](https://motoinstruction.ru/img/aprilia/17/122960.jpg)
Slide off the desmodromic drum control.
![](https://motoinstruction.ru/img/aprilia/17/122961.jpg)
Remove the three gear selection forks.
![](https://motoinstruction.ru/img/aprilia/17/122962.jpg)
Caution!
- The main shaft fork is smaller than those of the secondary shaft.
- All the secondary shaft forks are the same size.
![](https://motoinstruction.ru/img/aprilia/17/122963.jpg)
Carefully rotate the engine support.
![](https://motoinstruction.ru/img/aprilia/17/122964.jpg)
Carefully slide off the whole gear unit.
![](https://motoinstruction.ru/img/aprilia/17/122965.jpg)
Refitting
Repeat the removal operations but in reverse order, make sure that the shim washer is fitted to the secondary shaft.
![](https://motoinstruction.ru/img/aprilia/17/122966.jpg)