The size and KB can be changed by an admin, so something for schoon to look at probably. I'll admit, 6 Kb is somewhat 1992... still, plenty of guys have avatars here so it can obviously be done. Try saving as a GIF file as they are only 256 colour and make a smaller filesize.
EDIT: Linking offsite - mine is 100x100 pixels but it's about 18 Kb and a PNG so it's only restricted by filesize for uploads it seems.
For offsite, of course. GIF is the only way to get an uploadable one at the moment. 6 Kb is just ridiculous. You have to save as a GIF in MS Paint to get one that low in filesize at 100x100, and then it just looks like poop.