While custom ROMs like CyanogenMod 10 (CM10) or AOKP are great for a pure Android experience as found on Google’s Nexus devices but with added customization features, there’s no denying the fact that some people prefer a pure Android experience without any modifications and changes. The Galaxy S2, whose official Jelly Bean update has still not been announced by Samsung, has already seen quite a few Jelly Bean based ROMs come out for it, and we can now add another to the list.

XDA Senior Member cile381 has released a Jelly Bean ROM for the Galaxy S2 based on JRO03H, the latest Android 4.1 build for the Galaxy Nexus, without any modifications or bloat for a pure and stock AOSP Android experience as envisioned by Google for their Nexus devices.

The end result is that you get a fast and smooth ROM with all the new features of Jelly Bean – a smoother interface, advanced voice recognition, improved and actionable notifications, smarter keyboard, and a lot more. Do keep in mind that Jelly Bean custom ROMs are in their early stages, so a few bugs and issues are to be expected.

Let’s take a look at how the JRO03H-based Jelly Bean ROM can be installed on the Galaxy S2.

Compatibility

This firmware and the guide below are compatible only and only with Galaxy S2, model number I9100. It’s not compatible with the I9100G or any other device. Check your device’s model number in: Settings » About phone.

Warning!

The methods and procedures discussed here are considered risky and you should not attempt anything if you don’t know completely what it is. If any damage occurs to your device, we won’t be held liable.

How to Install JRO03H Jelly Bean ROM on Galaxy S2 I9100

  1. This procedure will wipe all your apps, data and settings (but it will NOT touch your SD cards, so don’t worry about those). Backup your Apps and important data — bookmarks, contacts, SMS, APNs (internet settings), etc. This Android backup guide would help you.
    Important! Don’t forget to at least make a backup of your APN settings, which you can restore later if your data connection does not work after installing the ROM. Use the backup guide to find out how.
  2. Install the stock Android 4.0.3 XXLPQ firmware on your phone by following the guide → here.
  3. Install Clockworkmod (CWM) recovery on XXLPQ by following the guide → here.
  4. Download the latest version of the ROM from its development page.
  5. Download the Google Apps package. This will install apps like Play Store, Gmail, etc. which are not present in the ROM by default.
    Download Gapps  |  Filename: gapps-jb-20120726-signed.zip
  6. Copy the 2 downloaded zip files from step 4 and step 5 to the internal SD card.
  7. Turn off the phone and boot into Clockworkmod recovery. For this, press and hold these 3 buttons together until the screen turns on: Volume UP + Home + Power. Phone will boot into CWM recovery.
    Use volume keys to scroll up and down between options and power key to select an option in recovery.
  8. Select wipe data/factory reset, then select Yes on next screen to confirm. Wait a while till the data wipe is complete.
  9. Select install zip from sdcard, then select choose zip from sdcard. Scroll to the ROM file on the SD card and select it. Confirm installation by selecting Yes – Install _____.zip on the next screen. The ROM will start installing.
  10. After ROM installation is complete, select choose zip from sdcard again, then select the kernel file to install the kernel.
  11. After ROM installation completes, select choose zip from sdcard again, then select the gapps-jb-20120726-signed.zip file to install the Google apps package.
  12. After the installation is complete, select go back then select reboot system now to reboot the phone and boot up into the ROM. The first boot can take up to 5 minutes, so be patient.
  13. NOTE: To go back to a stock Samsung ROM again, you can flash the XXLPQ firmware by following the guide linked in step 2 above, or flash to the latest Android 4.0.4 Samsung ROM by following this guide.

The JRO03H AOSP ROM based on Android 4.1 Jelly Bean is now installed and running on your Samsung Galaxy S2. Visit the official development page for more info and to get the latest updates on the ROM. Share your thoughts on the ROM in the comments.