Topic: question about Pod Filters?

[shane]

I installed my pod filters and there's tube coming off the engine to the OEM air box. Well I removed the airbox, and need to know what to do with this tube... I thought I read somewhere that it re-circulates unburned fuel. Do you guys usually use a breather filter of some sort?

here's  a pic

[Billiam]

I've seen a lot of people put a breather filter on there in place of the tube.  It looks like a mini-pod filter.  They sell em at most auto parts stores.

 http://www.sfxperformance.com/parts/SPT3995.htm#

[TwoTired]

The vapors that come out of the engine breather tube are carcinogens.  These vapors become less carcinogenic when burned in combustion chambers.

Any breather filter put on there simply keeps dirt and bugs outside the engine where they can be tortured and killed by the toxic vapors the engine crankcase still emits.

Cheers,

[shane]

The vapors that come out of the engine breather tube are carcinogens.  These vapors become less carcinogenic when burned in combustion chambers.

Any breather filter put on there simply keeps dirt and bugs outside the engine where they can be tortured and killed by the toxic vapors the engine crankcase still emits.

Cheers,

so are you saying no to a breather?  Another suggestion?

[seaweb11]

The vapors that come out of the engine breather tube are carcinogens.  These vapors become less carcinogenic when burned in combustion chambers.

Any breather filter put on there simply keeps dirt and bugs outside the engine where they can be tortured and killed by the toxic vapors the engine crankcase still emits.

Cheers,

In other words, your killing squirrels and small children

[eurban]

It is a good idea to put a filter on the end of the crankcase breather hose.  The engine will draw in some unfiltered air otherwise. . . .I think that TTs comments are more aimed at your choice to remove the airbox and install pods.  Along with issues like the need for jetting changes and increased crosswind and water susceptibility the switch to pods requires loosing the airbox's feature for recombusting crankcase fumes.  Why go to the trouble for a dubious performance mod? . . . BTW, I run "pod" filters on my bike but its for looks  . . .

[cgancos]

Are you referring to the hose coming off of the cylinder head breather cover?

[shane]

Are you referring to the hose coming off of the cylinder head breather cover?

yes

[MCRider]

Are you referring to the hose coming off of the cylinder head breather cover?

yes

On the earlier pre-emmissions CB750s (69-75 or so) that hose was vented to the atmosphere. It went horizontal from the rocker box, past the carbs and curved down to a hold clip right in front of the swingarm pivot.

It did not have any form of filter or valve on it at that point, I see no reason to put one on now.

The pressure out of the engine is neutral leaning to positive. little risk of sucking anything into that tube. Many other models actually plug the tube with a removable plug. Pull the plug once in a while to remove any oil that has condensed from the vapor coming from the tube.

On race bikes, none of which I have ever seen with a stock airbox, the hose is routed to a catch can, often a small OJ can taped to a frame rail. More for appearances than anything.

[cameron]

I drilled and epoxy-ed a little nipple into the bottom of my #2 pod, and attached that hose to it. So it could recirculate like it is supposed to.

[eurban]

Are you referring to the hose coming off of the cylinder head breather cover?

yes

On the earlier pre-emmissions CB750s (69-75 or so) that hose was vented to the atmosphere. It went horizontal from the rocker box, past the carbs and curved down to a hold clip right in front of the swingarm pivot.

It did not have any form of filter or valve on it at that point, I see no reason to put one on now.

The pressure out of the engine is neutral leaning to positive. little risk of sucking anything into that tube. Many other models actually plug the tube with a removable plug. Pull the plug once in a while to remove any oil that has condensed from the vapor coming from the tube.

On race bikes, none of which I have ever seen with a stock airbox, the hose is routed to a catch can, often a small OJ can taped to a frame rail. More for appearances than anything.

Actually the "breathing" term for crankcases is more accurate than you might imagine.  Its not a huge intake but it does pull in air. I also think you are missing some of the concept when it comes to the "plugged hose"  In these models (For instance the late SOHC 750s) the breather hose from the top of the valve cover goes to a separator that has two outputs.  A drain hose is attached at the bottom and is plugged, and the second upper hose routes the gases to the air filter box.  The plug is removed to drain out the nasty spooge that collects in the separator.  Many bikes have this setup and there really is no point in having a breather hose if it is simply a dead end with a plug on it.  Its either part of a vapor recovery system or perhaps (like in the earlier SOHCs) a conduit to route the gases and liquids down to the street, farther away from the rider.

[MCRider]

Eurban: I agree with your points.

On the CB750 (in line 4 with 180deg crank, 2 pistons up, 2 pistons down at all times) the breathing in and out is much more neutral than say a twin with a 360deg crank. And with ring blowby, its slightly positive virtually always.  Hence I say attention to sucking likely not an issue, but a filter on the end of the tube can't hurt.

Upon deeper reflection, yes the bikes I'm thinking of, my HawkGT for one, routes to the airbox first, and then to the drain tube which is plugged for periodical draining.

All performance Hawks have highly modified airboxes, or more likely pods, which Dyno runs prove are more efficient than the stock airbox, at least for HawkGTs, the emmissions breathers are routed to catchcans. I'm not sure if filters are used, there is a large sucking force in the crankcases as 2 pistons travel nearly together.

I like camn's idea of routing the hose into one of the pods. If the engine is healthy, little internal blowby etc, this shouldn't be a problem. One could even T it and run it into 2 or more of the pods, to spread out any ill effects.

To each their own.

[Lightning]

Add a flare stack

[jtsmith]

Add a flare stack

I run mine to my helmet so I can catch a buzz while I am riding!