I’ll try to be concise here,there is a question and pictures 
. I’ve been following the crankcase breather venting into the engine topic that’s discussed in thousands of places on the Web. General consensus seems to lean towards the “if you don’t put on a bypass with a catch can your motor will be toast in 10,000 miles.” Usually followed closely by a recommendation of their favorite setup. Not arguing one way or the other and I’ve seen the multiple pictures of crap encrusted pistons from TwinCams. Looked exactly like the crap encrusted pistons on my ‘78 Shovelhead Lowrider that vented to my chain. (Way it came, very handy chain oilier, thought it was a feature.) Rode the ‘78 Shovel for 33 years and would on occasion pull the heads off and clean the crap off the pistons. Unlikely I’ll be riding my ‘21 M8 Freewheeler for 33 years unless I live to 103.
Bear with me. At 2500 miles I replaced the stock HD air box with a Cobra PowerFlo Intake holding a K&N filter. I really liked the look of the HD box, just too big for me and I wanted a K&N filter, but wanted to keep the overall look of the box.
I kept the crankcase breather hose in the factory position. Went to the 5000 mile service that way. At around 6000 miles I was curious if they had “cleaned” my K&N Air Filter and took the cover off. It was practically spotless inside. OK. Since then I would occasionally see an oily film on the back of my air cleaner cover. I’d wipe it off and go about my business. This afternoon I decided to take the entire air cleaner unit apart. I’m at 9000 miles so let’s see. I left the two pics in question full size for examination.
On the vent hose you can clearly see a large drip of oil & moisture content. It hung there ‘till I wiped it off. Below the hose you can see where the oil is dripping on the intake, running down past the screw and dripping from the bottom of the mounting plate into the rubber bottom seal of the K&N filter. There is little or no oil in the filter pleats themselves. Lastly, you’ll see the drip line and collection of oil inside the bottom of the cover. This explaining the eventual film on the outside bottom and rear of the cover that I’ve been wiping off. Here’s the kicker. The inside walls of the intake and the butterfly had almost NO residue on them. Now I know a throttle intake isn’t a Kirby vacuum cleaner suction, but the lack of excessive residue seems to me like this particular Cobra PowerFlo Intake is acting like a rather large catch can? Maybe? Thoughts?
. I’ve been following the crankcase breather venting into the engine topic that’s discussed in thousands of places on the Web. General consensus seems to lean towards the “if you don’t put on a bypass with a catch can your motor will be toast in 10,000 miles.” Usually followed closely by a recommendation of their favorite setup. Not arguing one way or the other and I’ve seen the multiple pictures of crap encrusted pistons from TwinCams. Looked exactly like the crap encrusted pistons on my ‘78 Shovelhead Lowrider that vented to my chain. (Way it came, very handy chain oilier, thought it was a feature.) Rode the ‘78 Shovel for 33 years and would on occasion pull the heads off and clean the crap off the pistons. Unlikely I’ll be riding my ‘21 M8 Freewheeler for 33 years unless I live to 103. Bear with me. At 2500 miles I replaced the stock HD air box with a Cobra PowerFlo Intake holding a K&N filter. I really liked the look of the HD box, just too big for me and I wanted a K&N filter, but wanted to keep the overall look of the box.
I kept the crankcase breather hose in the factory position. Went to the 5000 mile service that way. At around 6000 miles I was curious if they had “cleaned” my K&N Air Filter and took the cover off. It was practically spotless inside. OK. Since then I would occasionally see an oily film on the back of my air cleaner cover. I’d wipe it off and go about my business. This afternoon I decided to take the entire air cleaner unit apart. I’m at 9000 miles so let’s see. I left the two pics in question full size for examination.
On the vent hose you can clearly see a large drip of oil & moisture content. It hung there ‘till I wiped it off. Below the hose you can see where the oil is dripping on the intake, running down past the screw and dripping from the bottom of the mounting plate into the rubber bottom seal of the K&N filter. There is little or no oil in the filter pleats themselves. Lastly, you’ll see the drip line and collection of oil inside the bottom of the cover. This explaining the eventual film on the outside bottom and rear of the cover that I’ve been wiping off. Here’s the kicker. The inside walls of the intake and the butterfly had almost NO residue on them. Now I know a throttle intake isn’t a Kirby vacuum cleaner suction, but the lack of excessive residue seems to me like this particular Cobra PowerFlo Intake is acting like a rather large catch can? Maybe? Thoughts?
