If a WordPress WXR file is too large to import then there are many ways to overcome that limit and import it. Some of them are as mentioned below:
* Break the WordPress WXR file into smaller pieces by separating the data between a posts and pasting the header into each file.
* Increase the PHP memory limit in php.ini by changing the memory_limit setting (e.g. memory_limit = 64M
* Increase the PHP memory limit via .htaccess (e.g. php_value memory_limit 64M)..
* Increase the PHP memory limit via wp-config.php (e.g. efine(‘WP_MEMORY_LIMIT’, ’64MB’);)