If you have a dual-core JiaYu G3 and aren’t all that impressed with JiaYu’s ROM updates you could take a look at this Android 4.2.2 MIUI ROM for your phone!
The ROM is for the original JiaYu G3 and G3N and brings all the functionality of Xiaomi’s MIUI ROM to the popular dual-core MT6577 Android smartphone. The ROM is an update of a previous version and brings a few bug fixes to the phone.
Please take care when installing new ROMs to your device so that you do not damage or void the warranty on your phone.
To download MIUI V5 3.9.13 for the JiaYu G3 hit this link, the password is: jpwy.[ Source ]