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Discussion Starter #1
OK - it's another one of my crazy ideas, but I wonder what would happen if instead of venting the crankcase to the air box it was vented with a slightly longer hose, possibly a slight bend and then capped with a small air filter?

Seriously, I wonder if it would reduce the pressure in the crankcase (thus reducing the downward resistance that the piston encounters) and not cause a problem (except a bit more pollution).

(Oh I so need to find a job that lets me use my imagination!)
 

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I did that on my Old Scooter, Put a Direct Small Mini Airfilter on to that Breather Hose! But there is OIL Steam coming out of the Crankcase which is being Pulled by the Airfilter it self, the Crankcase Tube or Port itself has no CFM flow.

Elliott,
 

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Discussion Starter #3
I did that on my Old Scooter, Put a Direct Small Mini Airfilter on to that Breather Hose! But there is OIL Steam coming out of the Crankcase which is being Pulled by the Airfilter it self, the Crankcase Tube or Port itself has no CFM flow.
So in other words, DON'T TRY IT, is that what you're saying?

Hmmm, the oil stream doesn't sound good - that sounds like a lot of pressure in the crankcase.
 

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The only consistent positive pressure in the crankcase is from combustion gasses blowing by (AKA "blow by") the piston rings, and this is rather slight in a normally operating/worn engine. Other than that there is none, as the equal and opposite movements of the piston(s) cancel out any pressure peaks--positive or negative--generated by those motions...

In fact, positive crankcase ventilation (PCV) systems exists because the small positive pressure created by blow-by is insufficient to keep the crankcase clear of the blow-by gasses which prior to PCV led to nasty sludge deposits in engines that were consistently not run up to full operating temperature, for long enough periods to boil off the nasties.

I.e. it is a good thing. However in the instance of the pre-'07 Burgman 400s 9and perhaps the later models as well?) the very short and relatively open path between the crankcase and intake allows an excessive flow of crankcase vapours that unfortunately includes excess quantities of atomized and/or vaporized engine oil--leading to increased oil consumption during sustained high speed operation:

Here is the PCV flow (and PAIR flow) for the pre-'07 400s, the latter models are not that different:



My contention, sustained by my insertion of a more restrictive PCV orifice, is that the OEM design PCV path is so short and so free-flowing that at high engine speeds the intake vacuum is literally sucking engine oil from the crankcase into the intake air flow...
 

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Discussion Starter #5 (Edited)
So are you saying that if there is a way to shrink the orifice that I should do that if the problem continues?

I've seen that orifice before - that hole is really tiny (at least it was on my old K5).

The K9 (and thus the K7 and K8) don't have a PAIR valve anymore. I'd attach a pic like yours but I can't seem to get anything to attach.
 

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I'd attach a pic like yours but I can't seem to get anything to attach.
get anything to attach, If you have a RED Bar on your attachments Page then your out of space Start by Deleting All files At least the stuff from the Old System

Sum of all attachments owned by happytech Size

if there is no Green in your Bar then your out of Space Upload File from your Computer

User CP

Attachments

Attachments Posted by happytech

Delete All Files in the Left Pane

Attachment Statistics

You are currently using XXX.X KB to store X uploaded attachments.

i think when the New system was first installed somebody Tried to Integrate Older files into the New System.


cliffyk, That's a nice Photo is this the 07' or 06 Model and is there an 07' Photo like the one you got any where...
 

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That is from the 2003 Service Manual, colour added by yours truly. FWIW my 2003 does not have the PAIR system as one of the first things I did was remove it all.

Here is a similar diagram from the 2007 Service Manual, with all flows colour coded:

 

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Thanks cliffyk,, I will save it to my Drive.

Elliott,
 

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Discussion Starter #9
Elliott,

This time they deleted, however, I still have two showing that don't offer an option to delete.

Looking at the old attachments, I need to do some playing with that crazy CVT cooling hose. Maybe I should try and rig up a 12 volt heavy duty fan somehow - or a straighter hose.

Of course, with leg shields, I wonder if that's helping to stop airflow.

Now, after this short off-tangent, back to our regularly scheduled thread.
 

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Discussion Starter #10
cliffyk, you must have a really good scanner!

On cars, you have an air intake in to the crankcase - on this, the only air intake is from the combustion process.

I've heard "enlarge the hole/remove the restrictor" and I've heard just the opposite.

Anyone have anything backed up with facts?
 

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I have a 97 Saturn. A common problem is that there is a breather hose that routes oil and gunk into the intake tract and the throttle body.

A common solution is to put a "puke jar" into the hose. Oil and gunk settle to the bottom. Gases go out the top and into the intake.

Applicable to the Burgman? I don't know.
 

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Discussion Starter #12
mike1nw, there's no room on the Burgman for that.
 
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