Gravatar is junk….

To remove it, add this toward the top of  your themes function.php

function bp_remove_gravatar ($image, $params, $item_id, $avatar_dir, $css_id, $html_width, $html_height, $avatar_folder_url, $avatar_folder_dir) {

	$default = '/avatarsdefault.png';

	if( $image && strpos( $image, "gravatar.com" ) ){ 

		return '<img src="' . $default . '" alt="avatar" class="avatar" ' . $html_width . $html_height . ' />';
	} else {
		return $image;

	}

}
add_filter('bp_core_fetch_avatar', 'bp_remove_gravatar', 1, 9 );
function remove_gravatar ($avatar, $id_or_email, $size, $default) {

	$default = '/avatars/default.png';
	return '<img src="' . $default . '" alt="avatar" class="avatar" width="60" height="60" />';
}

add_filter('get_avatar', 'remove_gravatar', 1, 5);

function bp_remove_signup_gravatar ($image) {

	$default = '/avatars/default.png';

	if( $image && strpos( $image, "gravatar.com" ) ){ 

		return '<img src="' . $default . '" alt="avatar" class="avatar" width="60" height="60" />';
	} else {
		return $image;
	}

}
add_filter('bp_get_signup_avatar', 'bp_remove_signup_gravatar', 1, 1 );

Then use User Avatar to allow the user to use their own avatar.

You can then modify the size of User Avatar’s avatars by modifying /wp-content/plugins/user-avatar.php

	if ( !defined( 'USER_AVATAR_FULL_WIDTH' ) )
		define( 'USER_AVATAR_FULL_WIDTH', 150 );

	if ( !defined( 'USER_AVATAR_FULL_HEIGHT' ) )
		define( 'USER_AVATAR_FULL_HEIGHT', 175 );