Installation:

1. Open OpenIV
2. Go to GTA V/x64e.rpf/levels/gta5/vehicles.rpf
3. create backup of:

scorcher
scorcher+hi


4. Extract files from this zip to a folder
5. Make sure to enable edit mode.
6. Replace these files with the Giant Bike:

scorcher
scorcher+hi

7. Enjoy! :D