yeah, after so many years and bikes and miles without any single issue related to this topic I don't see the need to educate myself on its stated or perceived merits..if it ain't broke, keep riding I say
10-4 on not reading anything and learning something new.
Was really enjoying reading this thread and learning a little something about the use of a catch can. Have an 03EG with a mild set of cams and punched out and completely understand that it's not a requirement for a stock twin cam, but I think any little bit you can do helps. Normally clean the IAC once or twice a year and things are good to go.
Enjoyed the pictures @07UltraGuy posted. Nice job with using a combination of AN fittings, the small breather filter, the catch can, and the custom bracket.
Saddened to see the thread take a bit of a down turn. Oh well...at least I learned something
I externally breath all of my bikes.. Every engine is going to experience blow by. The air oil separators in the heads aren't perfect. Yeah, good ring seal blah blah blah but ring seal is also dependent on a fully warmed up engine. What happens until then and what happens when an engine is warming up? What happens when oil is warming up and starts to burn off the water? I have seen what is in larger catch cans and I don't want that going through my engine. Valves don't need extra lube. If they did. I would lube them with corn fuel over discharge from breathers.
On another note. I have never seen any reason to filter the air coming out of the engine either. With the one way check valves in the heads or inline with external breathers. There is no reason to filter air before it hits atmosphere. What I have seen happen. Oil makes dirt stick to filter and clogs them. Then you are venting this pressure out of seals. Usually the main single lip seal of the output shaft into the primary or base orings.
...There is no reason to filter air before it hits atmosphere. What I have seen happen. Oil makes dirt stick to filter and clogs them. Then you are venting this pressure out of seals. Usually the main single lip seal of the output shaft into the primary or base orings.
I modified things a bit over the 'just vent it to atmosphere approach' for a few reasons.
1- I hated the constant oil drip line down the timing cover, and wanted to eliminate that, along with addressing the IAC issue.
2- I was a bit skeptical that the small holes in the lid of the catch can were sufficient to allow the pressure to dissipate without sending out a mist of oil, water, and mildly pressurized air onto the side cover, etc. essentially just moving the problem from inside the air cleaner/intake, to the side of the bike and my leg.
3- I punched a hole through the filter material, inserted a custom vented stem (to allow the exhausted air mixture to get to the bottom of the catch can before being restricted by the filter), then I added an 'upstream' filter element to simply reduce any back pressure that the catch can & fittings might have created.
All of this allows me to run the bike at full oil capacity without getting the mess of the oil blow by in the intake, or on the the timing cover. I could have accomplished this with a rubber hose and a clamp or two, but that would not have looked as good or kept me busy for as long.
In mjwebb's defense...as indifferent as his posts appear, I can guarantee that he read that thread long ago. It was posted in 2012. He stays pretty current on things. Harleys loading up with carbon due to a crappy crank ventilation system is a very old "issue". In truth it really doesn't matter all that much. Yes you can reduce carbon on the piston and keep gunk out of the IAC and throttle body. Modern bikes don't suffer much. FWIW, this was my answer to a catch can:
In mjwebb's defense...as indifferent as his posts appear, I can guarantee that he read that thread long ago. It was posted in 2012. He stays pretty current on things. Harleys loading up with carbon due to a crappy crank ventilation system is a very old "issue". In truth it really doesn't matter all that much. Yes you can reduce carbon on the piston and keep gunk out of the IAC and throttle body. Modern bikes don't suffer much. FWIW, this was my answer to a catch can:
yeah, I'm guilty of being a little abrasive, ..but like you said..it's an age old topic that is less relevant today...fuels, oils, tolerances, FI and ECMs are more efficient, etc..just trying to offer a voice of reason about it...had a crew chief from his nat'l championship top fuel Harley drag bike tell me once, that even the M8s need to be wound up often to blow the carbon out the old fashion way, and that a lot of the problems are a result of too many thinking these are just torque monsters and end up never riding over say 3000-3500 rpms..that is not good for the motor, they need to be ridden hard in the upper rpm range as they are designed to be..think too many people keep reading about doing these mods and feel they need to, and perhaps still don't ride them the proper way..oh well..continue on folks..sorry for the disruption, again
02-09-2022 | 12:26 PM
