I agree with laws of gravity but the original holes to drain the oil into the throttle body aren't at the bottom and the oil does not seem to pool. So not sure it really matters. Hoping that by letting it breath better I will not get any oil in the first place.
I was thinking of trying a 45 degree fitting on one side to maybe reduce the strain at the filter. If that does not work I my try the holes at 90 degrees and see how it works.
I have an S&S Stealth and my fittings are angled approximately 30 degrees to make routing easier. I have put thousands of miles on with no issues. I did the same to my buddy's Heavy Breather.You should have no problems.The crankcase vents the misty oil mixed with the puff of pressure so I believe the mist to take the easy path as long as you have the original drain ports blocked that drain to the throttle body opening. I tapped the original passage from the throttle body side, installed a set screw with red locktite and the plugged the sunken set screw with rtv as an added measure.
No need to do mine. No leaks, no blow by, no blow back, no leakage what so ever.
Arlen Ness Big Sucker 1 for going on 5 years and not 1 ISSUE.
Works GREAT!!!
I cannot stand the look of those rubber tubes and oil catch containers!!
So I have been working on my breather by pass. I wanted something that would look good and be easy to take apart and clean. I thought I would try using AN fittings and hose.
I drilled and tapped the back plate and used AN 6 to 1/8" NPT. Then I used several AN fittings to then attached to a breather.
I like how stiff he set up is but the AN hose is short and does not flex alot.
I drilled my holes off center to cleat the throttle body and angle with the short hose isn't the best
Do the holes need to be at teh bottom or can they be off the sides? The holes that currently bring the oil and mist into the throttle body are at 90 degrees. My set up would work much better if I drilled the holes opposite the original holes.
I had to shorten the hoses the original length I used the breather was to low.
Interesting thread here, thanks to everyone for posting. I really like the looks of this setup. As far as why couldn't the holes be drilled off to the side? I am thinking it may truly work better that way. I really don't believe that the purpose for the breathers is so much for the oil to properly drain out, (law of gravity) but more to simply relieve crankcase pressures. If the holes were drilled 90* from where you have them and towards the top of the original ports it seems to me that more of the liquid would tend to stay in the engine & drain back into the heads while still relieving the needed pressure. I am thinking out loud here, why does the vent breather need to be below the TB? hmmmmm,,,,,
Last edited by DHubbs; 11-16-2014 at 12:02 PM.
Reason: thinking out loud comment
I'll take a SWAG at it. First I just went with what I thought would look best, Hidden/unseen. The Crankcase must be vented in some way. HD went with dumping it down the intake to help comply with EPA mandates/regs.(it seems to work ok for autos but not so good in a V-twin air cooled motorcycle) Anyways the hot air also has oil vapor and water vapor in it. Every time the bike is shut down and cools off what little moisture in the air condenses in the cases, So as soon as oil temp gets back up to 212 deg that condensed moisture turns to steam and is blown out the vent with a bit of oil mist. When vented into the TB the steam is sucked in the intake as soon as it enters the cavity between your air filter and backplate,Some oil sticks to the backplate, and builds up enough to start dripping past the intake opening and saturating the air filter until it drips on your motor,pipes,sidecovers etc... As far as venting through a hose at some point that vapor condenses into a thick gooey gunk (Thats a scientific term) So once the flow has started it seems logical to keep it going downhill so it doesn't build up in a low spot or "trap" and cool some more and clog the vent. Which is why I tried to keep hose length as short as possible.But others have had good results with long hoses venting to the ground as far back as the rear axle with small humps/dips/curves along the way. Who knows...Now I'm thinking out loud.
I'll take a SWAG at it. First I just went with what I thought would look best, Hidden/unseen. The Crankcase must be vented in some way. HD went with dumping it down the intake to help comply with EPA mandates/regs.(it seems to work ok for autos but not so good in a V-twin air cooled motorcycle) Anyways the hot air also has oil vapor and water vapor in it. Every time the bike is shut down and cools off what little moisture in the air condenses in the cases, So as soon as oil temp gets back up to 212 deg that condensed moisture turns to steam and is blown out the vent with a bit of oil mist. When vented into the TB the steam is sucked in the intake as soon as it enters the cavity between your air filter and backplate,Some oil sticks to the backplate, and builds up enough to start dripping past the intake opening and saturating the air filter until it drips on your motor,pipes,sidecovers etc... As far as venting through a hose at some point that vapor condenses into a thick gooey gunk (Thats a scientific term) So once the flow has started it seems logical to keep it going downhill so it doesn't build up in a low spot or "trap" and cool some more and clog the vent. Which is why I tried to keep hose length as short as possible.But others have had good results with long hoses venting to the ground as far back as the rear axle with small humps/dips/curves along the way. Who knows...Now I'm thinking out loud.
Well, that is what these forums are good for. As long as we are both thinking out loud, lemme run a idea past ya that I conjured up some time ago while thinking about this very thing. This may have already been tried and failed, I donno, just a thought. Ya'll give me your thoughts on this. What if there was a O2 sensor bung type fitting welded in the exhaust head pipe behind the existing o2 sensors and the cat area. What if stainless braid hose was routed off the heads to a Y fitting and finally to a orificed fitting that is screwed into the welded fitting in the exhaust. The exhaust gasses rushing by this orifice would create a venturi type effect theoretically creating a slight vaccum inside this braided tubing, helping to relieve the engine with any back pressure. This being located behind the O2 sensors and the cat, it would not interfere with them. No oily mess dripping under the bike. Possibly a slight puff of smoke every now and then out the mufflers as a drop of oil enters it and burns off. What ya'll think??? Rainy night in Ga. here, nuttin else to do.
Good idea, could/should work.barring any backflow/pressure from exhaust going in. Maybe some kind of BFP valve like in plumbing. But that might complicate things by clogging or sticking open/shut. The pulses/timing of exhaust and the vent could compliment each other or compete with each other, Depending on the length of hose and position of bung. Harley probably couldn't develope such a system. Unless burning the vapors off in the exhaust vs the combustion chamber satisfied the EPA.
But I'd be interested in seeing someone try it.
Well, that is what these forums are good for. As long as we are both thinking out loud, lemme run a idea past ya that I conjured up some time ago while thinking about this very thing. This may have already been tried and failed, I donno, just a thought. Ya'll give me your thoughts on this. What if there was a O2 sensor bung type fitting welded in the exhaust head pipe behind the existing o2 sensors and the cat area. What if stainless braid hose was routed off the heads to a Y fitting and finally to a orificed fitting that is screwed into the welded fitting in the exhaust. The exhaust gasses rushing by this orifice would create a venturi type effect theoretically creating a slight vaccum inside this braided tubing, helping to relieve the engine with any back pressure. This being located behind the O2 sensors and the cat, it would not interfere with them. No oily mess dripping under the bike. Possibly a slight puff of smoke every now and then out the mufflers as a drop of oil enters it and burns off. What ya'll think??? Rainy night in Ga. here, nuttin else to do.
You wouldn't want any pull against the umbrella seals.
11-16-2014 | 08:50 AM
