If you wish to undertake maintenance to your GAS GAS SM 125 Halley then it is always a great idea to have a Workshop Manual for a reference just in case you need to know the best ways to take off a specific part for example, the Wheel Bearing and install it again the right way.
GAS GAS SM 125 Halley Workshop Manuals will give you unique diagnostic guides for the car therefore if something is not working it helps you discover what the issue is and the way to resolve it. You will be able to determine if you can do this by yourself or that the job is simply too big you can still book your SM 125 Halley into a local mechanic.
GAS GAS SM 125 Halley manual