Restore System Partition

[anewa]

I was jailbreaking my iPod 4 with greenpois0n RC6 but when I tried the loader, the internet failed and I had to restore and re-jailbreak a couple of times. Finally after a couple of tries I could download cydia but I noticed that the system partition was filled 63%. I want to know if there is any way to restore this partition to it's original state when it only had iOS 4.2.1 and no jailbreak because I think the remnants of the other failed installations are there taking up a lot of space.

 

[Crypton]

The System partition is only 750MB, mine is filled up to 92.5%.
AFAIK after a restore both partitions should be back to their "normal" size.