From Eclipse, go to Window | Preferences | Install/Updates | Available Software Sites; from there, uncheck (disable) the following components:
Motodev Plugins
MotodevPlugins
Sequoyah Metadata Repository
https://studio-android.motodevupdate.com/android/4.0/
https://studio-android.motodevupdate.com/android/4.0/basic/
https://studio-android.motodevupdate.com/android/4.1/
Sequoyah is an old independant component that is usually installed before Motodev because it's needed for Motodev. It is no longer maintened and probably that you should remove it as well after removing Motodev.
The last three in the list are not designed here by the name of their componenent but by their location as they are unnamed sites. (At least, they are unnamed on my personal installation). You should also check carefully for any other sites related to either Motodev or Sequoyah.
After that, not only you shouldn't have any more error but the update checking should perform much more faster.
BTW, when you are there, take the time for checking for other older, unused components/versions.