The fitting at the top of the engine goes to the side of the filter box (NEVER the air plenum chamber). The filter box also has a drain tube at the bottom that is capped. The cap has a slit in it, that is pinched at maintenance intervals to drain collected water condensate.
The bottom of the filter box has the parts you see in the picture you posted. Those parts; gasket, foam element, and metal assembly are there to keep the engine vapors from fouling the air filter element. It will ruin the stock paper element very quickly with oil and water vapors/droplets. The foam UNI type will survive this much better, but the cleaning and re-oiling interval will shorten.
Cheers,
I stumbled upon this thread while looking at options to replace my air filter, and thanks to it I realized when I installed my stock airbox (bike came with pods) I hooked up the hose wrong, to the air plenum chamber as you said never to do. I've been riding it around and it's been running pretty good, what are the results of having the hose hooked up here? Running richer from burning oil vapors differently than if they went through the air box, or risk of condensed liquid oil building up and getting sucked in, or what?
When everything works perfect, the engine breather to plenum connection will work ok for the interim, I suppose. I never attempted to run it this way.
It's when the carb bowls overflow with gas that the risks become significant, as that air plenum drain tube is supposed to route pooling gas under and away from the bike, rather than filling the plenum chamber, and engine cylinders/oil sump with gasoline.
A plenum filled with gasoline, and a backfire though the carbs might just ruin your day. But, it
IS thrilling to live life on the edge and take any risk that comes along.
I prefer to minimize risks, as there are plenty of things that can go wrong even if one doesn't rearrange things that aren't fully understood.
