Crank case breather

[Jared]

Can someone explain to me the benefit of having a crank case breather vs letting it breath into you air intake? Only benefit I am aware of is it keeps you filter cleaner longer.

What the main reason for them?

[Monkeyman]

If you're blowing any oil, then the external filter will keep the oil from going back into the chamber and....something. Gadget or Eurekaboy did a pretty good write up on it. Plus, the external filter just looks COOL! I have a filter but it didn't come with a bracket. I'll have to source one this winter and add it when I pull the tank and do all the other stuff (intake, coasters, fuel proc, etc).

Yup...Gadget had it. Here's a quote:

"When blowby occurs on an engine using a crankcase vent routed into the air filter (which is the case with Vulcan's), oil makes its way through the engine breather into the air cleaner [or airbox in our case] and is then pulled into the engine along with the fresh intake charge and burned. That oil tends to carbon up the rings and glaze the cylinder walls resulting in a less than perfect top end seal. Once this occurs the die is cast. The poor top end seal leads to more blowby which pushes even more oil into the intake air which is then forced into the engine creating more blowby and so it goes."

Here's the link to the complete write up >> http://www.gadgetjq.com/cc_breather.htm

[ringadingh]

I doubt it will make any difference at all, the hose for the breather is already inside the air filter, so the oil vapours are not getting filtered regardless.
It may help keep the throttle body a bit cleaner, but thats the only advantage I see.

[Monkeyman]

Have you ever seen a chrome crankcase breather filter? Or you have something personal against shiny stuff? It looks cool and costs next to nothing. How can you go wrong? lol:)

[Jared]

Originally Posted by ringadingh

I doubt it will make any difference at all, the hose for the breather is already inside the air filter, so the oil vapours are not getting filtered regardless.
It may help keep the throttle body a bit cleaner, but thats the only advantage I see.

That was my impressions. There the millions of cars and bikes whose vapours go into the air filter and it hasn't been a problem.

I'm sure Monkeyman is correct in saying that it as more to do with looks than anything else.

[MAS Tequila]

In my case, with an open element filter, it makes a lot of noise when vented into the the air filter. So that is the biggest reson I have mine vented through a breather.

MT

[Cajunrider]

I plan on adding a breather on mine. Since going with the open right side, I occasionally find a drip or two of motor oil on the engine side cover. It is coming from the intake breather hose and drips through the bottom of the K&N filter. Funny thing is it doesn't do it all the time.

[Jared]

Originally Posted by Cajunrider

I plan on adding a breather on mine. Since going with the open right side, I occasionally find a drip or two of motor oil on the engine side cover. It is coming from the intake breather hose and drips through the bottom of the K&N filter. Funny thing is it doesn't do it all the time.

Wouldn't it just drip from where ever you put the breather?

[Jared]

Originally Posted by MAS Tequila

In my case, with an open element filter, it makes a lot of noise when vented into the the air filter. So that is the biggest reson I have mine vented through a breather.

MT

What kind of noise does it make? Perhaps I'm hearing it, but not knowing?

Mostly what I hear with the open filter is the throttlebodies sucking the air. To me is sounds like your spaying air with an air compressor, in a pulsing pattern.

[Cajunrider]

Originally Posted by Utah Motorcyclist

Wouldn't it just drip from where ever you put the breather?

It wouldn't drip from an external breather. There would be no vacuum to pull enough oil to accumulate and drip. Clean the breather assembly every oil change or whenever it appears dirty/oily. The chrome breather assembly looks good and eliminates the buildup of condensed oil vapors in your intake. The only downside I've heard about the external breather is that you will occasionally or always detect the distinctive crankcase odor. I suppose placement of the external breather would make a difference.

[trosco]

Actually Positive crankcase ventilation which is using the vacum in the intake track down stream from the filter to suck out hydrocarbon vapors that nomally occur in a engine crankcase is one of the most significant advances in polution control and a side benefit is it cleaned up the overheads of our motors. Defeating that system is foolish. Just my opinion

[krash]

Originally Posted by trosco

Actually Positive crankcase ventilation which is using the vacum in the intake track down stream from the filter to suck out hydrocarbon vapors that nomally occur in a engine crankcase is one of the most significant advances in polution control and a side benefit is it cleaned up the overheads of our motors. Defeating that system is foolish. Just my opinion

Is there a PCV valve on the Nomad?
Some vapors from the crank case would be drawn into the intake but I don't see where it would be very efficiant and would gum up the throttle body.
From what I see the breather hose from the air cleaner just allows filtered air to enter the motor and let vapors out. If thats the case an external filter would do the same job, keep the intake cleaner and maybe get rid of that extra noise in the Chuckster intake I have installed.

JMHO from an old school back yard mechanic.

[trosco]

Rick, air flow in this situation is just the oposite of what you are thinking. The crankcase is presurized and the intake side of the air cleaner is below Atmospheric pressure. So the vacumn effect exerted on the hose opening at the cleaner assembly is sucking oil vapors coming from the super heated oil in our motors and combustion vapors that move past our rings out of our motors. That keeps our internals cleaner. And because they get then burned and subsequently processed in the exhaust based polution controls it keeps the air we breath cleaner too.
Equally important is that it reduces pressure in the crankcase of our motors. Pressure in our motors hit much higher peaks and valleys because our pistons can both be in the up stroke or down stroke at same time. On the up stroke should pressure in the crankcase get below the -12 to 15 Atmospheres in the cleaner assembly (highly unlikely) you may suck some air into the engine case but because it's already been through the air filter it will be clean. On the down strokes pressures could be several times Atmospheric levels were it not for our positive crankcase ventilation system. It's where a lot of the parasitc power loss comes from in engines like ours.
The 45 degree V-twin is an ineffficient power design but great for space and riding position on a motorcycle. When you compare it to say: a in line 4 with 90 degree offset crank throws or a boxer type design. Both of which make lots more HP at similar diplacements but it's dam difficult to get our riding position when you have their their type motors occupying where we want our feet and legs.
Gadget's info (my opinion) is useful WHEN you have enough engine wear in the oil/compression ring and cylinder wall area that you are headed toward a rebuild but want to slow down that process a bit. Otherwise the tatic is not in the best interest of your motor or your lungs.