All right, here goes: You can get the perfect sized filter at advance auto. Get one for an Import car valve cover. I got one there before ever coming here, I thought I was smart until I saw that everybody had one. You can get one for $10 at advance. You won't have any problem with water or oil by doing this. Your weak point is the air box lid. I run a half-lid with a k&n and outerwear but I've seen water get into lidded air boxes so I don't even try it. If I new there was going to be water and mud I would put the stock filter back on with lid. Minimum get an outerwear and clean filter after every ride without airbox lid.

 

all good points thanks for the info...

 

Think about this. As the oil and air in you engine gets hot it expands and air goes out the breather hose and when it cools the opposite happens everything contracts sucking air back in the engine. I don't know about where you all ride but where I ride it's usually dusty or there's a good chance the sand is blowing and I don't want a 1/2" hose without a filter on it going into my engine sucking in all that. It's not a bad idea to have it on there when the engine is running either. If there's a way into your engine dirt and sand will find it.

 

The main, if not only source of this air coming out of this breather hose is blow-by from combustion. These crankcase fumes are routed back into the airbox to reduce pollution. When drawn back into the combustion chamber and burnt, these fumes may be detrimental to the engine over time. As the engine wears, the crankcase fumes consist of blow-by from the combustion chamber and oil deposits. This can, over time, cause deposits on the head surface, pistons and valves. The crankcase can be vented outside the engine by removing the breather hose. To prohibit flow back into the crankcase, automobiles use a PCV valve. This valve will allow gasses to leave the crankcase and enter the intake, but under boost conditions as seen with a turbo, will not allow air to enter back into the crankcase. As far as my knowledge goes, there should not be any form of pressure forcing air into the raptors breather hose.

 

the reason the hose is located in the snorkle/air inlet is because it is operating on the same principle as a carburator. As air is drawn in via the airbox inlet it creates a negetive presure at the tip of the crankcase hose. This causes the crankcase fumes/pressure to be drawn out of the crankcase and recycled/reburnt in the engine. It is called crankcase evacuation. The more the merry. Professional race teams use this therory to make more horespower. The actually use a belt driven vacuum pumps on their engines to maintain a vacuum in the crankcase. this allows the piston rings to seat better which in turn allows them to use less tension on the rings. Less tension means less friction and less friction means more power. It also reduces emmisions .