Engine vents?
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Joined: Oct 2010
Posts: 73
Likes: 1
From: Springfield, MO
Engine vents?
I have read the stock engine vents into the air cleaner and can cause the piston to get nasty in short order.
Some of the aftermarket air cleaners eliminate the engine rebreathing the vented gas.
Is there anyway to do this with the stock system. I want to get an aftermarket air cleaner, but am undecided, and I want to ride with the stock system for a while without screwing up the engine.
Thanks
Some of the aftermarket air cleaners eliminate the engine rebreathing the vented gas.
Is there anyway to do this with the stock system. I want to get an aftermarket air cleaner, but am undecided, and I want to ride with the stock system for a while without screwing up the engine.
Thanks
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,897
From: Bedford UK
It is true that some aftermarket air cleaners for Harleys do that, but is it necessary? No. Don't lose any sleep, vehicles the world over vent into their air cleaner and have done so for decades. My aftermarket S&S engine vents into it's air filter and hasn't given any problems either.
Road Master
Joined: Feb 2007
Posts: 781
Likes: 35
From: St Louis
Very true, but having torn down my Evo years ago and two TC's prior to my current motor with a breather, the difference in condition of the piston heads, intake manifold/throttle bodies is dramatic. I figure i spent money to improve the performance of my engine and if something that cost me about $25 can route hot oily air somewhere other than my engine air intake, why not. It may be only a slight improvement but worth it IMHO
Stellar HDF Member
Joined: May 2007
Posts: 3,251
Likes: 515
From: USA
I too would like a stealthy solution with a stock ham-cam air filter cover.
DK Products sells these beautiful hollow bolts with foam, screen and a snap ring that replace the long OEM bolts that extend into the air cleaner backing.
I think the cost is $40. Do a search.
From post # 2, I think he is saying you then need to cap the holes in the air cleaner housing that these OEM bolts inserted into if you install the DK bolts. I do not know about clearance issues.
In my case, I don't wish to modify the air cleaner backing plate.
So, I am wondering if just inserting some foam tightly into the OEM bolts would work or whether engine vacuum (or even heat issues) will cause the foam to be ingested and or fail. Conservatively, I think it will not be a sage idea.
Therefore, I am still looking for ideas, hence I am "in" for this thread's responses!
DK Products sells these beautiful hollow bolts with foam, screen and a snap ring that replace the long OEM bolts that extend into the air cleaner backing.
I think the cost is $40. Do a search.
From post # 2, I think he is saying you then need to cap the holes in the air cleaner housing that these OEM bolts inserted into if you install the DK bolts. I do not know about clearance issues.
In my case, I don't wish to modify the air cleaner backing plate.
So, I am wondering if just inserting some foam tightly into the OEM bolts would work or whether engine vacuum (or even heat issues) will cause the foam to be ingested and or fail. Conservatively, I think it will not be a sage idea.
Therefore, I am still looking for ideas, hence I am "in" for this thread's responses!
Extreme HDF Member
Joined: Dec 2007
Posts: 13,402
Likes: 941
From: Illinois
It is the crankcase breather. With blow buy from the combustion chamber the crankcase gets pressurized so it needs venting. In the old days it was just vented to the atmosphere.
Now with EPA it must be routed into the intake manifold to be reburned. It has oil mist and hot gasses in it. Robs the engine of a pony or two and carbons up the engine fast. I pulled the head on a twin cam at 7,600 miles and there was a thick build up of carbon.
The route to the manifold is holes in the bolts that hold the air cleaner on.
A forum sponsor DK Customs has a great kit to correct the problem. Just click on their link at the top of this page.
You can not just plug the bolts the crankcase gasses MUST be routed out to a catch can or mesh filter. Both will be need cleaning. Block the holes and go for a ride and watch the engine destroy itself.
All engines sold to install for use on the roads have the crankcase vented to the intake. All of them period. Its the law.
Now with EPA it must be routed into the intake manifold to be reburned. It has oil mist and hot gasses in it. Robs the engine of a pony or two and carbons up the engine fast. I pulled the head on a twin cam at 7,600 miles and there was a thick build up of carbon.
The route to the manifold is holes in the bolts that hold the air cleaner on.
A forum sponsor DK Customs has a great kit to correct the problem. Just click on their link at the top of this page.
You can not just plug the bolts the crankcase gasses MUST be routed out to a catch can or mesh filter. Both will be need cleaning. Block the holes and go for a ride and watch the engine destroy itself.
All engines sold to install for use on the roads have the crankcase vented to the intake. All of them period. Its the law.
Last edited by lh4x4; May 4, 2016 at 06:01 PM.
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I have read the stock engine vents into the air cleaner and can cause the piston to get nasty in short order.
Some of the aftermarket air cleaners eliminate the engine rebreathing the vented gas.
Is there anyway to do this with the stock system. I want to get an aftermarket air cleaner, but am undecided, and I want to ride with the stock system for a while without screwing up the engine.
Thanks
Some of the aftermarket air cleaners eliminate the engine rebreathing the vented gas.
Is there anyway to do this with the stock system. I want to get an aftermarket air cleaner, but am undecided, and I want to ride with the stock system for a while without screwing up the engine.
Thanks
We have a selection of External Breather Systems, they can be see at this LINK.
The specific EBS for the Stock Sportster Air Cleaner is this ONE.
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DKCustomProducts.com
DKCustomProducts.com
Last edited by DK Custom; May 5, 2016 at 02:18 AM.
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Thread Starter
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Advanced
Joined: Oct 2010
Posts: 73
Likes: 1
From: Springfield, MO
You are correct, recirculating hot, oily, oxygen depleted air into the air cleaner is self-defeating. Engines run best on cool, clean, oxygen rich air. Will your engine blow up if you don't vent externally. No. Will it run stronger, and last longer if you do vent externally? Yes. See the pics and charts of the differences at either of the links below.
We have a selection of External Breather Systems, they can be see at this LINK.
The specific EBS for the Stock Sportster Air Cleaner is this ONE.
We have a selection of External Breather Systems, they can be see at this LINK.
The specific EBS for the Stock Sportster Air Cleaner is this ONE.
I took my stock air cleaner off last night and the stock backing plate has plastic nipples that push inside the factory air cleaner. inside those nipples are the factory breather bolts.
How they have it set up on my bike, I do not see how it is possible to externally vent the engine. You would have to attach a hose to the nipples on the backing plate, run then inside the factory air cleaner, then try to route them back out with factory air cleaner and backing play, all the while trying to keep the seal air tight.
I went ahead and ordered an air cleaner from DK. He said I wouldn't have to do any ecm calibrations to just run an air cleaner. This was my concern as I am still undecided on an exhaust and wanted to ride it without worry of fouling up the engine while I decide.
Cruiser
Joined: Oct 2015
Posts: 125
Likes: 8
From: MN
I took my stock air cleaner off last night and the stock backing plate has plastic nipples that push inside the factory air cleaner. inside those nipples are the factory breather bolts.
How they have it set up on my bike, I do not see how it is possible to externally vent the engine. You would have to attach a hose to the nipples on the backing plate, run then inside the factory air cleaner, then try to route them back out with factory air cleaner and backing play, all the while trying to keep the seal air tight.
I went ahead and ordered an air cleaner from DK. He said I wouldn't have to do any ecm calibrations to just run an air cleaner. This was my concern as I am still undecided on an exhaust and wanted to ride it without worry of fouling up the engine while I decide.
How they have it set up on my bike, I do not see how it is possible to externally vent the engine. You would have to attach a hose to the nipples on the backing plate, run then inside the factory air cleaner, then try to route them back out with factory air cleaner and backing play, all the while trying to keep the seal air tight.
I went ahead and ordered an air cleaner from DK. He said I wouldn't have to do any ecm calibrations to just run an air cleaner. This was my concern as I am still undecided on an exhaust and wanted to ride it without worry of fouling up the engine while I decide.