Parts needed:3/4"X1/2" clear vinyl tubingFram FV 401 PCV valve or equivalent or a reducing elbow 1/2" to 3/8"Flapper valve from the catch-canPlastic tiesRoute the timingcase breather tubing and secure with ties as pictured in the second photo.
tooseevee,On the timingcase breather tubing, I just left it open. If you are concerned, you could put a duckbill flapper valve on the open end. Nfieldgear has them for $5.95, part number 140167. It will be in the performance section. If you route the breather tubing from the timingcase high and out of the weather, not low like I did, a little round filter would work just fine. If you route the breather tubing down low like I did, I would not use a filter. It will just get wet and clog-up if you ride in the rain or mud or wet streets or ford streams and such, I love the mud. Cheers,Bill
I believe the duckbill is there to restrict the air from entering your crankcase, but allowing pressure to vent. The only 4 stroke bikes I have ever owned that did not have some form of checkvalve were big twin Harley's. They had a rotary valve built into the oil pump drive. A whole lot of trouble, kinda think it may serve a pourpose.