CB air filters

Hi just need a little advice, my carbs are running a little lean but before I start tuning them need to make sure everything else is running ok, it has twin weber 40 idf with CB air filters, the air filters to my knowledge were fitted two years ago and so was just wondering how to clean them and maintain them, can't seem to find any information on doing it.
Thanks

 

K&N air filters are washable . You can by special stuff to clean them

 

Or use Pipercross - K&N competitor, comes with the cleaning spray.

 

These look like you can clean them but not sure, I was tempted to by new ones like k & n but if I can service these then no need