[Dmraco]

I am removing the air box on my 81 CM400C and going with pod filters. I noticed the motor has a cam cover vent that went to the air box.

For people that have done this what did they do with this vent? Would placing a filter on it work or should I route the hose to the underside of the motor?

 

[longdistancerider]

You'll want to add a breather filter like these https://www.knfilters.com/vent.htm or a catch can.
For a filter the best spot is mounted above the valve cover fitting so the oil that get blown out can drain back into the engine. Yes, oil does get blown out in the for of oil/air mix and once it hits the filter it'll separate, this causes the filter to become an oil drip source.
For a catch can it can be locate anywhere convenient. Basically any can will do, insert the hose into the can and have a secondary hole to let the air vent out. Best if you can insert a pot scrubber into the can like these https://www.ebay.com/itm/Scrubbies-...=item4b4b53c99e:g:bywAAOSwQvhZhMnH:rk:10:pf:0 so the oil can separate from the air. NOTE: the catch can has to be drained periodically like at oil changes. Here's some instructions on making one https://www.instructables.com/id/Oil-Catch-Can-DIY/