Actually, Barons says vent the crankcase breather down through the frame. Here's a nice post from their forum that explains things better than I could myself.
"The rear cylinder has 2 breather hoses connecting to the top valve cover. The rear one goes to the oil tank. The front one attached to your original air cleaner. You probably connected this hose to the white nylon nipple on the back of the
BAK. The vacuum in the BAK tends to suck the oil vapors from this hose and foul the filter. Don't worry, this can be cleaned. You should get some 5/16 or 3/8 hose from the auto parts store, about 5 feet. I know that is probably too much but it is cheap and you don't want to run short. Also buy some 3/8 inch vacuum caps. Take the breather hose off the white nipple on the rear of the BAK and cap the white nipple with one of the 3/8 inch vacuum caps. put the new hose on the metal nipple coming off the top of the rear valve cover and route it to the ground.
You probably don't need to put a filter on this hose but alot of guys do. I bought a chrome fuel filter that comes apart for replacing the filter element. I removed the copper filter element and stuffed some white foam breather filter material in it so it breaths easier. The filter material is from a 2" x 4" automotive breather filter element, Fram I think. I just cut a half inch corner off to put in the fuel filter housing and I have plenty left for future replacements. This filter is small so you don't need to mount it or anything like that. I routed my hose under the tank and through an opening behind the transfer cover behind the rear cylinder. Check other posts to see how they routed theirs."
I'm one of those guys that put a filter on the hose. I bolted it using the same attachment as the back horn. You need a slightly longer bolt, but the stock ones you took off when replacing the air box fit perfectly. Oh, and get the 3/8 hose..the 5/16 liked to kill me getting it on the filer if you buy one.
Here's a link for the filter I put on.
http://www.phatperformanceparts.com/merchant2/merchant.mvc?Screen=PROD&Product_Code=14-20900<br><br>Post edited by: jmonette, at: 2006/06/16 11:22