the filter is probably for a breather hose. looks to small for an air filter so that must be what it's for. can use them on any kind of breather but with that one you will need a metal sleeve to clamp the filter and hose to. the hose looks like it is being used as a breather. it releases excess pressure. that is what people are putting on their heads. the stock fifty has a crankcase breather. thats what the black hose going into stock airbox is. if you use an aftermarket filter it is a good idea to put a breather over it. some people don't run filters on their head breathers but i do.
I have a UNI filter and i cut the crancase breather hose and left it open. Is that were you attach a breather hose? Should i attach a breather filter there? Also I am getting that breather hose that goes on i think the intake valve. Should i add a filter there too? Last would i be able to add a hose like in the second pic? Is there any benefits to adding filters on the hoses?
I have a hose with K&N filter there because I run a K&N filter on my carb. I like to think that they run the crankcase breather into the airbox because they don't want dirt to get sucked in in the case of back pressure. If I was you I would put a hose and filter on it. I also run a filter on my head (valve cover) breather. A lot of people don't because there is not a lot of back pressure, but I run one to be safe. XR/CRF50's are bullet proof and I like to keep them that way. I guess you could run a hose off your dipstick, but I think it would be a waste of energy. There is already a breather on the crank. It's a 50 and there is no way that it could build that much pressure. If you want to go ahead, but run a filter if you do. I just don't have that much time on my hands.
OK thanks for the help. I will put a filter on the crancase breather and the valve one. Yea i agree i think it is not necessary to put one on the dipstick. Do you oil and clean the filter or is it enough to leave them not oiled? Also where do you attach the hose and filter for the crankcase one?
the black hose that comes out of the case. it went into the airbox. you can use the stock hose and put one on or you can pull the stock hose off and get a new one. there is a little fitting toward the back on top of the case.
i made my own tho, just got a copper pipe about 1 inch diameter and cut "pie slices" out of one side so it would funel down and put in a smaller pipe the fit inside my head breather and crankcase hoses. then i put a lil hot glue inside to fill in the seems (lol) and gav it a lil paint, and cut a sponge to use as a filter 8) :roll:
one question tho, my xr70 carb has a vent house coming out of it should i put a filter on that too?