Ducati Monster Forum

Moto Board => Tech => Topic started by: Ducsauce on February 20, 2010, 09:50:25 AM

Title: Crankcase breather pros and cons?
Post by: Ducsauce on February 20, 2010, 09:50:25 AM
 Okay so Ive been trolling through posts and many people seem to say to do the crankcase breather by pass for performance and cosmetic appearance. I can understand the cosmetic aspect but Im still confused about OVERALL performance gains, if any. Allow me to clear up any questions I can before I begin. I have a 2001 M750, bone stock. Carbuerated not fuel injected. It still has all the emissions cans and the little pod thingys on the side of the frame. I was just going over options for modifying and one of the easiest things seems to be the crank case breather.

1. My experience with motors is limited to my cars. Ive built show cars. I know some parts Ive put on the car were for "show only". The crankcase breather has always been one of those "show only" mods. Im no mechanical genius but I do know that the crankcase is vented into the intake in order cause a positive vacuum that increases oil flow into vital moving parts. If it wasnt designed to do that why would Ducati have it there?

2. How much of a real world gain can be actualized by this mod?

3. What damage can it cause over the long term use of such a thing? I know that in my cars it can lead to failure in the head and such not.

4. How, if at all, will this affect overall reliability of my machine?

I understand that the crankcase breather has the potential of venting "oily mist" back into the intake but after checking the area immediately around the port into the intake box that there is no buildup which is usually associated with any kind of worry that there will be damage to the motor. If anything I would assume that the oil thats that fine would help to aid in the lubrication in any parts in the top end more than cause any kind of harm.
Sorry if this seems simple to most but I dont want to take the chance of blowing my bike up through something that could have been left the heck alone! Thanks in advance all!!
Title: Re: Crankcase breather pros and cons?
Post by: ducpainter on February 20, 2010, 09:54:58 AM
There is some disagreement about the performance gains.

I don't believe there are any, and on 4V bikes there is actually a performance drop.

It's small, but proven.

Lots of bikes run with the filter with no long term ill effects.

Make it look like you want and be happy.
Title: Re: Crankcase breather pros and cons?
Post by: Ducsauce on February 20, 2010, 10:24:47 AM
Yes Im super new to all this, do I have 2V or 4V?   ???
Title: Re: Crankcase breather pros and cons?
Post by: ducpainter on February 20, 2010, 10:27:06 AM
Quote from: Ducsauce on February 20, 2010, 10:24:47 AM
Yes Im super new to all this, do I have 2V or 4V?   ???
Your 750 is a 2V air cooled.

All the 4V Ducs are water cooled
Title: Re: Crankcase breather pros and cons?
Post by: Howie on February 20, 2010, 05:09:09 PM
Ditto on what ducpainter said.  Positive crankcase ventilation is required by law, it also prevents oil from being burped out, possibly on your rear tire.  The reasons for eliminating the breather box are aesthetic or you need to for other modifications like pod filters.  If you do choose to eliminate the breather box mount the filter high up to avoid oil burps.
Title: Re: Crankcase breather pros and cons?
Post by: He Man on February 20, 2010, 05:26:37 PM
If you could find a way to extend the neck of a pod filter by some length and plastic weld a nozzle onto it, you could directly connect the crankcase to the the intake.
Title: Re: Crankcase breather pros and cons?
Post by: Privateer on February 20, 2010, 09:47:20 PM
i'm wondering if there's a way to replace the ugly plastic tank with something a little more pleasing, maybe hang it off the frame with a clamp.  I want to flip my rectifier over so it gets more cooling, but have to ditch the tank for that which I'd rather not do.
Title: Re: Crankcase breather pros and cons?
Post by: Langanobob on February 21, 2010, 02:47:01 AM
QuoteIm no mechanical genius but I do know that the crankcase is vented into the intake in order cause a positive vacuum that increases oil flow into vital moving parts.

I'm ready to be corrected on this, but I don't think the crankcase vacuum has much to do with increasing oil flow into vital engine parts.  Plenty of oil flows into vital moving parts due to oil pump pressure and the crankcase pressure doesn't have much to do with it.  But I could be misguided.

I think the positive crankcase ventilation does help to minimize the amount of wayward combustion chamber gases contaminating the oil.  Years ago I hooked up a positive system on my old '66 Triumph which has a huge amount of crankcase gases compared to a Duc and it's worked fine with the additional benefit of stopping the legendary Britbike oil leaking.  I was concerned it would foul plugs, but no.

I like Privateer's idea of a better looking tank.  .
Title: Re: Crankcase breather pros and cons?
Post by: Howie on February 21, 2010, 03:05:38 AM
Quote from: Langanobob on February 21, 2010, 02:47:01 AM
I'm ready to be corrected on this, but I don't think the crankcase vacuum has much to do with increasing oil flow into vital engine parts.  Plenty of oil flows into vital moving parts due to oil pump pressure and the crankcase pressure doesn't have much to do with it.  But I could be misguided.

I think the positive crankcase ventilation does help to minimize the amount of wayward combustion chamber gases contaminating the oil.  Years ago I hooked up a positive system on my old '66 Triumph which has a huge amount of crankcase gases compared to a Duc and it's worked fine with the additional benefit of stopping the legendary Britbike oil leaking.  I was concerned it would foul plugs, but no.

I like Privateer's idea of a better looking tank.  .

You are not wrong in either statement, though I'm not sure about the effect of oil cleanliness on a Duc, since there is always positive pressure in the crankcase, you are running a filter as good as an air intake filter and the valve is still there. 
Title: Re: Crankcase breather pros and cons?
Post by: Privateer on February 21, 2010, 06:26:36 AM
Quote from: Langanobob on February 21, 2010, 02:47:01 AM
I like Privateer's idea of a better looking tank.  .

after some searching around, something like this, but smaller.  this one is 6" long.
(http://www.eliteengineeringusa.com/all-colors.jpg)
Title: Re: Crankcase breather pros and cons?
Post by: fouramdesigns on February 21, 2010, 08:21:23 AM
I installed the TPO kit, I have some oil blowback, pools around the base gasket area. Spoke with TPO, he things the reed in the breather is bad. I just had the infamous base gasket leak repaired, so when I first saw this, I was worried.
Title: Re: Crankcase breather pros and cons?
Post by: Howie on February 21, 2010, 10:33:01 AM
Quote from: fouramdesigns on February 21, 2010, 08:21:23 AM
I installed the TPO kit, I have some oil blowback, pools around the base gasket area. Spoke with TPO, he things the reed in the breather is bad. I just had the infamous base gasket leak repaired, so when I first saw this, I was worried.

Could be, sometimes a reed will even break.  If you still have the OEM valve, the valve itself could be leaking.
Title: Re: Crankcase breather pros and cons?
Post by: scott_araujo on February 22, 2010, 02:01:14 PM
I didn't think that was a tank between the crankcase valve and air cleaner, I think it's just a baffled chamber.  The vapors always get sucked into the air cleaner but if you get an oil burp the liquid never gets past the baffles and drains back to the case.

Am I wrong?

Scott
Title: Re: Crankcase breather pros and cons?
Post by: ducpainter on February 22, 2010, 02:05:42 PM
Quote from: scott_araujo on February 22, 2010, 02:01:14 PM
I didn't think that was a tank between the crankcase valve and air cleaner, I think it's just a baffled chamber.  The vapors always get sucked into the air cleaner but if you get an oil burp the liquid never gets past the baffles and drains back to the case.

Am I wrong?

Scott
You're correct.

Title: Re: Crankcase breather pros and cons?
Post by: stopintime on February 22, 2010, 02:06:46 PM
Quote from: howie on February 20, 2010, 05:09:09 PM
Ditto on what ducpainter said.  Positive crankcase ventilation is required by law, it also prevents oil from being burped out, possibly on your rear tire.  The reasons for eliminating the breather box are aesthetic or you need to for other modifications like pod filters.  If you do choose to eliminate the breather box mount the filter high up to avoid oil burps.

If the filter is mounted directly on the valve, like most I've seen, where will a burp go? Into the filter, clogging it or through the filter making a mess? (tire?)
Title: Re: Crankcase breather pros and cons?
Post by: scduc on February 22, 2010, 02:32:03 PM
I also went the way of the TPO kit and after installing it, I noticed that something just wasn't right with the performance. She stuttered every now and then. I went back to the stock config, and the issue went away. Now, I have been told with the FI models, some tuning may be needed, so when I have the exhaust done, I will try it again. I had this done with my 00' 750, and never had a problem.
Title: Re: Crankcase breather pros and cons?
Post by: Howie on February 22, 2010, 10:23:29 PM
Quote from: stopintime on February 22, 2010, 02:06:46 PM
If the filter is mounted directly on the valve, like most I've seen, where will a burp go? Into the filter, clogging it or through the filter making a mess? (tire?)

Not a matter of will, could make a mess.  If you don't suffer excessive blowby, overfill the oil or wheelie down the block all will be fine.  As far as the filter clogging, unlikely as long as you clean it every now and then.
Title: Re: Crankcase breather pros and cons?
Post by: GAAN on June 19, 2010, 02:27:09 PM
Would there be any issue with running the hose straight from the breather valve to the airbox and bypass the tank under the seat?
Title: Re: Crankcase breather pros and cons?
Post by: Howie on June 19, 2010, 05:46:26 PM
Quote from: Mother on June 19, 2010, 02:27:09 PM
Would there be any issue with running the hose straight from the breather valve to the airbox and bypass the tank under the seat?

Part of the breather box's job is to separate liquid from vapor.  The other is to supply ample volume.
Title: Re: Crankcase breather pros and cons?
Post by: ducatiz on June 19, 2010, 06:45:22 PM
Quote from: Mother on June 19, 2010, 02:27:09 PM
Would there be any issue with running the hose straight from the breather valve to the airbox and bypass the tank under the seat?

This is how it is done on older bikes and there isn't THAT much problem, however hose length and breather connection might play into that.   The hose on my Pantah 650 engines is factory and is about 2 ft long.  The Pantahs used a different breather too -- which is compatible with the later models -- that is completely flat on the engine. 
Title: Re: Crankcase breather pros and cons?
Post by: GAAN on June 19, 2010, 07:06:15 PM
well I got curious and cut the tank open

I can recreate the same function inside the airbox

I think...hope
Title: Re: Crankcase breather pros and cons?
Post by: Javamoose on June 19, 2010, 08:55:55 PM
Quote from: ducpainter on February 22, 2010, 02:05:42 PM
You're correct.

So, if it's just an open baffled tank (and you wanted to keep the can, but dress it up, smaller, etc), couldn't you just use a nice looking billet overflow tank?  Like this:
(http://static.summitracing.com/global/images/prod/large/csi-932b_w.jpg)

Replace the drain fitting with another hose-barb fitting?  Mounted with the IN port at the bottom, the oil (if it burped) shouldn't get sucked up and eventually would drain back into the case...
Title: Re: Crankcase breather pros and cons?
Post by: RAT900 on June 19, 2010, 09:34:20 PM
My old Carb'd 96 M900 did NOT benefit from the TPO setup...

there was a noticeable drop-off and I went back to the stock system inside of 2 days and the bike went back to running better....

I don't know how the balance of positive and negative pressure created in the crankcase and the intake air box respectively work to improve things as a system...but they do

I have not bothered dicking around with the set-up on my 02 900ie bike....

but I would welcome a decent aftermarket canister that would free-up some space and give me some options for getting fresh air to the rectifier

I would think the input and output hose fittings would need to be the same O.D. as the stock set-up

I would jump on something like that if one came along
Title: Re: Crankcase breather pros and cons?
Post by: GAAN on June 20, 2010, 12:05:44 AM
I dunno about the hoses needing to be the same size, the hole underneath the reed valve in the breather is teeny tiny
Title: Re: Crankcase breather pros and cons?
Post by: ducatiz on June 20, 2010, 02:50:17 AM
I bet you could find one of those old scool pcv filters with a hose barb. They used to poke thru a hole in the air cleaner holder with a clip to hold it securely. You'd need a new hole in your air cleaner.  Ill post a link.  They put them outside the filter tho which might be hard esp if you've trashed the cover
Title: Re: Crankcase breather pros and cons?
Post by: scott_araujo on June 20, 2010, 02:24:35 PM
Quote from: ducatiz on June 19, 2010, 06:45:22 PM
This is how it is done on older bikes and there isn't THAT much problem, however hose length and breather connection might play into that.   The hose on my Pantah 650 engines is factory and is about 2 ft long.  The Pantahs used a different breather too -- which is compatible with the later models -- that is completely flat on the engine. 

Just running some more hose should help some.  It's unlikely to completely fill with oil which means it will just burp a little bit up which should drain down on its own.  A smaller baffle inside the air box like Mother is planning would likely work with a long, large diameter line run to it.  Probably really easy to solder something together from sheet copper.  Now you've got me thinking...

Scott
Title: Re: Crankcase breather pros and cons?
Post by: ducatiz on June 20, 2010, 03:03:18 PM
This is what I was referring to:

http://www.aaaaautomotive.com/Shop/Control/Product/fp/SFV/32785/vpid/6720760/vpcsid/0/rid/134382 (http://www.aaaaautomotive.com/Shop/Control/Product/fp/SFV/32785/vpid/6720760/vpcsid/0/rid/134382)

The whole thing sits INSIDE the air cleaner box, with the spigot/barbed bit coming out the side for connection to a hose.

THe clip goes on the spigot to hold it in place.

VERY common on 1970's American cars..
Title: Re: Crankcase breather pros and cons?
Post by: Howie on June 20, 2010, 04:37:28 PM
Quote from: ducatiz on June 20, 2010, 03:03:18 PM
This is what I was referring to:
http://www.aaaaautomotive.com/Shop/Control/Product/fp/SFV/32785/vpid/6720760/vpcsid/0/rid/134382 (http://www.aaaaautomotive.com/Shop/Control/Product/fp/SFV/32785/vpid/6720760/vpcsid/0/rid/134382)

The whole thing sits INSIDE the air cleaner box, with the spigot/barbed bit coming out the side for connection to a hose.

THe clip goes on the spigot to hold it in place.

VERY common on 1970's American cars..

Most cars with Positive Crankcase Ventilation allow air into the crankcase as well as blowby gasses out.  Typical is filtered air enters the cranckase through a device like in your link and blowby exits the crankcase through a hose to the intake manifold controlled by a PCV valve or a small orifice.  Most cars run with negative pressure (vacuum) so a provision is needed for fresh air.  Ducatis need a big area to collect the (hopefully) slight positive pressure, which is why the breather box is there, just check out the sized of a Corsa breather box. 
Title: Re: Crankcase breather pros and cons?
Post by: corey on June 20, 2010, 04:42:15 PM
have had my filter on for 3500 miles, not a single drop out of it. no performance drops or anything...
Title: Re: Crankcase breather pros and cons?
Post by: ducatiz on June 20, 2010, 04:50:20 PM
Quote from: howie on June 20, 2010, 04:37:28 PM
 

Most cars with Positive Crankcase Ventilation allow air into the crankcase as well as blowby gasses out.  Typical is filtered air enters the cranckase through a device like in your link and blowby exits the crankcase through a hose to the intake manifold controlled by a PCV valve or a small orifice.  Most cars run with negative pressure (vacuum) so a provision is needed for fresh air.  Ducatis need a big area to collect the (hopefully) slight positive pressure, which is why the breather box is there, just check out the sized of a Corsa breather box. 

I am pretty sure that filter is for stuff coming out of the engine, not going in.  The filter protects the air filter for the carb from getting spoiled with oil.  At least that's how it was on my old Ford.

Direct hose from the valve cover goes to that air filter thingy.  Later models had a reed valve type setup like you describe, IIRC.
Title: Re: Crankcase breather pros and cons?
Post by: GAAN on June 20, 2010, 08:05:01 PM
the hose on the monster goes into the airbox under the filter so the recirculated crankase air is unfiltered

so I don't think you would need anything like a PCV

all one would need to build is a fluid trap of some kind

preferably outside the airbox

I'm thinking a CO2 type expansion chamber for a paintball gun would serve the purpose well

and

look pretty cool and be quite a bit smaller than the previous posted option

the way the stock box is structured, it only needs to be able to hold a max of 3oz of fluid

it would also allow one to use braided line vs. that ugly rubber stuff

a pair of 4oz chambers might have enough space to mimic the stock system

(http://images.auctionworks.com/hi/55/54922/xp5046a.jpg)
Title: Re: Crankcase breather pros and cons?
Post by: He Man on June 20, 2010, 09:15:06 PM
I ran the crank case breather hose directly to my airbox. Theres more than 3fl oz of space in the hose itself, any oil ( and there shouldnt be that much oil) that is blowing out of there will end up inside the tube, which will eventually slide back down into the system.

I had that setup for a few thousand miles and just recently went to a breather filter since i ditched the airbox for pod filters. Already put about 800 miles on it, i dont have any oil blowback. I dont overfill, and i do an occasional power wheelie once or twice a week. No issues so far.
Title: Re: Crankcase breather pros and cons?
Post by: scott_araujo on June 20, 2010, 10:38:04 PM
Mother, that's not nearly geeky enough.  There's got to be a way to do this with an Altoids box.  :P

Scott
Title: Re: Crankcase breather pros and cons?
Post by: GAAN on June 21, 2010, 12:30:19 AM
Quote from: scott_araujo on June 20, 2010, 10:38:04 PM
Mother, that's not nearly geeky enough.  There's got to be a way to do this with an Altoids box.  :P

Scott


I suppose you could braze an altoid box into a vessel...

Title: Re: Crankcase breather pros and cons?
Post by: Raux on June 21, 2010, 12:52:40 AM
i think if there is no outlet to vent the pressure you would eventually get a blow out.

the older TT had a tube that went to a box under the battery. basically it captured the oil on one side to allow it to flow back and had an escape for the air on the other.

_______
|        _ air out >
|------|
|        |
|____o|

this is the top of the box... the 'o' is a tube going down to the oil breather. the '-' is a tall wall inside the box that almost goes to the top. the oil goes in the one side but there isn't enough pressure to push it to the other side but the air escapes.

Title: Re: Crankcase breather pros and cons?
Post by: Howie on June 21, 2010, 02:08:13 AM
Oil in the air filter on your old Ford is sign of either excessive blow by or a clogged/poorly operating PCV valve, or, at least in theory.  Truth is, sometimes the systems did not work well enough in the real world to prevent this, so most cars would have a light film in the air cleaner.

Below is a test procedure for that type of system.  In this case, blow by gasses enter under the carb, still manifold vacuum. 

http://home.sprynet.com/~dale02/vac-pcv.htm (http://home.sprynet.com/~dale02/vac-pcv.htm)

A back yard test way before closed loop and OBD II was to remove the oil filler cap and place a piece of paper over the opening with the engine running at idle. If the paper is drawn towards the opening, all is good.  Away from the opening, you have excessive crankcase pressure.

When you have a small crankcase compared to piston displacement, like on a Ducati you always have positive crankcase pressure, therefore the typical car system becomes irrelevant.  The valve is there to control the pressure, keeping it low enough to prevent seals and gaskets from failing and reduce horsepower loss.  The breather box allows sufficient storage for the crankcase vapors until the engine can burn them. 
Title: Re: Crankcase breather pros and cons?
Post by: floyd turbo on June 21, 2010, 02:33:49 AM
Thank you howie
Title: Re: Crankcase breather pros and cons?
Post by: ducatiz on June 21, 2010, 02:40:59 AM
I am sure you are correct about the pcv setup, it's been a long time.

I mentioned that filter as an option for us to pipe the pcv hose directly into the airbox.  Since it will come in "under" the filter.  It should be easy enough to cut a hole and put in the grommet for the filter mount.  It may even create more vacuum in the crankcase though, which may or may not be a good idea..
Title: Re: Crankcase breather pros and cons?
Post by: ♣ McKraut ♣ on June 21, 2010, 03:46:13 AM
Quote from: scott_araujo on February 22, 2010, 02:01:14 PM
I didn't think that was a tank between the crankcase valve and air cleaner, I think it's just a baffled chamber.  The vapors always get sucked into the air cleaner but if you get an oil burp the liquid never gets past the baffles and drains back to the case.

Am I wrong?

Scott

unless you run it without the filler cap on for a few minutes... it seriously will dump some oil into your air box (and mist it all over the right side of the bike).  ask me how i know.
Title: Re: Crankcase breather pros and cons?
Post by: Rock Store on June 21, 2010, 07:43:57 AM
Another look at it,
http://www.ducati-upnorth.com/tech/breather.php (http://www.ducati-upnorth.com/tech/breather.php)
later..RS
Title: Re: Crankcase breather pros and cons?
Post by: Two dogs on June 21, 2010, 02:05:20 PM
I have installed a K&N breather on my 695 not for cosmetic reasons
but due to a suspension upgrade as the shock piggy back would not fit
so the regulator was moved and breather box had to go.

I keep a constant look at it for and oil and as the 695 does not get up on the rear wheel
as much as larger capacity bikes unless the fuel tank is very low  [laugh] and the bike is in 1st gear.
Should I remove it and clean it often checking for excessive oil ?
Or has this thread made me a little paranoid about oil misting on the rear tyre?

Title: Re: Crankcase breather pros and cons?
Post by: scott_araujo on June 21, 2010, 02:30:25 PM
I think checking on it once in a while is a good idea.  You should make sure the one way valve is still working.  For the filter, well, you'd basically take it off, clean it, and re-oil it.  Since it's not drawing air in because of the one way valve and it's getting continuously oiled by the oil vapor passing through it, what more needs to be done?  I would think a quick inspection would suffice.

Scott
Title: Re: Crankcase breather pros and cons?
Post by: Howie on June 21, 2010, 07:49:02 PM
Quote from: dezmonster on June 21, 2010, 02:05:20 PM
I have installed a K&N breather on my 695 not for cosmetic reasons
but due to a suspension upgrade as the shock piggy back would not fit
so the regulator was moved and breather box had to go.

I keep a constant look at it for and oil and as the 695 does not get up on the rear wheel
as much as larger capacity bikes unless the fuel tank is very low  [laugh] and the bike is in 1st gear.
Should I remove it and clean it often checking for excessive oil ?
Or has this thread made me a little paranoid about oil misting on the rear tyre?



Lots of bikes out there are running your set up.  As long as you don't overfill the crankcase, develop excessive blowby or put too much oil on the filter you will probably be OK.  Mounting the filter as high up as possible will also help.
Title: Re: Crankcase breather pros and cons?
Post by: suzyj on June 21, 2010, 09:35:53 PM
Quote from: dezmonster on June 21, 2010, 02:05:20 PM
I have installed a K&N breather on my 695 not for cosmetic reasons
but due to a suspension upgrade as the shock piggy back would not fit
so the regulator was moved and breather box had to go.

I keep a constant look at it for and oil and as the 695 does not get up on the rear wheel
as much as larger capacity bikes unless the fuel tank is very low  [laugh] and the bike is in 1st gear.
Should I remove it and clean it often checking for excessive oil ?
Or has this thread made me a little paranoid about oil misting on the rear tyre?

Geez Dez.  I only did the mod because you did, and now I'm gonna die because oil will end up on my rear tyre, and it'll all be your fault!

I think you should put your stock rear shock back in, and put your crankcase breather canister thingy back as soon as possible.

Naah, seriously, I haven't noticed so much as a skerrick of oil coming from the breather, and I've been keeping close tabs on it.  The canister was also quite dry when I took it off.
Title: Re: Crankcase breather pros and cons?
Post by: Two dogs on June 21, 2010, 10:36:00 PM
Suzy  [evil]

my personal stalker ;D
If you would like me to come over and check your crankcase just give me the word [laugh]
Title: Re: Crankcase breather pros and cons?
Post by: ♣ McKraut ♣ on June 22, 2010, 02:51:01 AM
Quote from: dezmonster on June 21, 2010, 10:36:00 PM
Suzy  [evil]

my personal stalker ;D
If you would like me to come over and check your crankcase just give me the word [laugh]


you should probably check out her expansion chamber as well...
Title: Re: Crankcase breather pros and cons?
Post by: ducatiz on June 22, 2010, 02:54:33 AM
Quote from: ♣ McKraut ♣ on June 22, 2010, 02:51:01 AM
you should probably check out her expansion chamber as well...

well if that's how you roll..

an "expansion chamber" is another name for an exhaust.

http://en.wikipedia.org/wiki/Expansion_chamber (http://en.wikipedia.org/wiki/Expansion_chamber)

Title: Re: Crankcase breather pros and cons?
Post by: suzyj on June 22, 2010, 12:01:01 PM
Quote from: ducatiz on June 22, 2010, 02:54:33 AM
an "expansion chamber" is another name for an exhaust.

Why would Dez want to check that?  Does oil from the breather get on the exhaust?