Crankcase vent vacuum setup removal = bad

[hunduc]

For the reasons listed just above this post and below yours, primarily. If you think about it, it makes since: Air is in the crankcase, when the pistons travel 'down' they need to be able to move that air out of the way. In the stock venting system, the air box and intake are 'pulling' that air out of the way.

I would imagine that the smaller the displacement and shorter the stroke the less it makes a difference, but i got other things on the mind right now to think too much into it.

i removed mine for clutter reasons. just like the airbox.

for performance i'd leave it on, and not only stick with an airbox, but creatively enlarge mine.

so the only reason you wouldn't do it again is performance, right?

did you feel the drop in performance when you removed the stock system?

[junior varsity]

i may figure out how to do that eventually. starting with pre-02 frame carbies.  

EVR doesn't do it, there's probably a reason. Likely #1 reason, most monster owners aren't really after high dollar more power when its easier to go for a SBK or naked SBK

It would be very interesting to see how one might make a tank/airbox design with different filter position more like the 748-998 superbikes (bottom of tank was lid of airbox)

[junior varsity]

so the only reason you wouldn't do it again is performance, right?

did you feel the drop in performance when you removed the stock system?

hell if i know. i did that around the same time i put on some performance goodies (like lightweight flywheel), so there's no way of knowing.

i am concerned about a longterm wheelie dumping out my precious oil on my back tire. less concerned about the oil making me wreck or causing another accident, but that's my damn oil and i'll keep it as long as i care to.

[hunduc]

A thought; opening the air box will probably reduce the vacuum draw on the crankcase hose anyway. Probably works better on the stock air box. Hope I'm wrong. 
Anyone read anything that addresses this?

i think you are right there. i have the dp ecu, hence the open airbox.

[hunduc]

less concerned about the oil making me wreck or causing another accident, but that's my damn oil and i'll keep it as long as i care to.

that damn oil, trying to escape any way it can. 

[koko64]

i think you are right there. i have the dp ecu, hence the open airbox.

With the open air box, at lower revs there will still be some vacuum and therefore an advantage over venting to the atmosphere. With the open air box, at high revs there will be even more air rushing over the opening of the breather hose creating a greater vacuum draw on the crankcase. So at low revs a little advantage, but at high revs it works well and that's when you need it. That's what I keep telling myself.

Someone may have actually tested this to know for sure.

[ungeheuer]

Thoroughly interesting read from beginning to end 

May throw a little light on my extremely minor crankcase breather oil "leak" (calling it an actual leak is a serious overstatement, its a minor weepage really).  I have WASPworks airbox-be-gone PUK fitted to my 09 M1100, meaning that the stock hose connected to the stock crankcase breather is no longer connected to the airbox for the entirely obvious reason.  Instead, at the end of the stock hose I have a cute, lil' weiner of a K&N. 

So here's the issue: My oil weepage seems to be coming from the join in the crankcase breather itself (I originally thought it was coming from between crankcase and breather).  Could it be that - in the absence of any induction induced vacuum - that oil which has got beyond the breather's reed valve rather than being scavenged up into the airbox for future combustion (my understanding is becoming a bit dodgy here) is collecting in the hose above the reed valve, eventually weeping out between the breather's join (at the point where its assembled around the reed valve)?  Long winded question there I know, hope it makes some sense  .

[stopintime]

AFAIK there is a small hole next to the valve, so any oil should run back. Probably not all of it and probably with a short delay. Maybe enough to leak out? Anyway, a leak should be fixed, yes?

[ducpainter]

Thoroughly interesting read from beginning to end 

May throw a little light on my extremely minor crankcase breather oil "leak" (calling it an actual leak is a serious overstatement, its a minor weepage really).  I have WASPworks airbox-be-gone PUK fitted to my 09 M1100, meaning that the stock hose connected to the stock crankcase breather is no longer connected to the airbox for the entirely obvious reason.  Instead, at the end of the stock hose I have a cute, lil' weiner of a K&N. 

So here's the issue: My oil weepage seems to be coming from the join in the crankcase breather itself (I originally thought it was coming from between crankcase and breather).  Could it be that - in the absence of any induction induced vacuum - that oil which has got beyond the breather's reed valve rather than being scavenged up into the airbox for future combustion (my understanding is becoming a bit dodgy here) is collecting in the hose above the reed valve, eventually weeping out between the breather's join (at the point where its assembled around the reed valve)?  Long winded question there I know, hope it makes some sense  .

You just have a weepy valve.

Remove it, clean it up, and seal the joint with clear silicone and it will stop.

[ducatiz]

You just have a weepy valve.

Remove it, clean it up, and seal the joint with clear silicone and it will stop.

red silicone will make the bike faster

[junior varsity]

pretty much stopintime and DP hit the nail on the head. They used to leak all the time - mine was doing a bad job so I replaced it with a nichols one but they seem much better now. If you want to bling it out, you can always get a billet one.

or use red silicone.

[battlecry]

The air velocity in the 2V airbox is not that high.  If you open up a few holes on the cover, the flow is in the order of less than  16 MPH at 9K RPM.  If the airbox velocity is less than air velocity around the bike when it is moving, using it as a source of vacuum may be silly.  You may be better off using a venturi with the faster airflow down the sides of the bike.

You must do two things, vent the excess pressure from the crankcase (or your bike will turn into a Triumph, and no offense intended), and not allow any oil to leak into the rear tire.  Anything else is gravy, driven by practical considerations.

If you do not want to carry the canister, don't.   I have a long hose from the crankcase reed valve to the rear of the bike, capped with a low pressure one way check valve.  The check valve allows the positive crankcase pressure to vent to a low pressure area.  I don't use a filter, gas flows out.  The long hose helps some of the oil vapors to condense and fall back through the drain hole in the reed valve.  Haven't checked to see if the hose holds a slight negative during piston rise, but it probably is better than the stock setup.  Some superbikes do something similar, gutted the reed from the crankcase and connected the hose to a second one way valve and then that to the airbox.



 

[671M900]

make the beast with two backs. My bike came to me in pieces, nothing on the damn crank case breather. Not to mention it's setup with pods for FCR41's, there was no airbox included. How the hell do I retain the crank case vent system?

[hunduc]

make the beast with two backs. My bike came to me in pieces, nothing on the damn crank case breather. Not to mention it's setup with pods for FCR41's, there was no airbox included. How the hell do I retain the crank case vent system?

as soon as you go the pod way i guess the original vent system is out. the oem system vents into the airbox - no airbox, no venting there. it might be possible to rig up some strange system where your blow-by somehow goes back to the air intake (maybe with hoses), but i have never heard anybody doing that for a monster.

you might be able to try to go back to the very original airbox-oil breather box setup by finding them on fleabay...   

[ducatiz]

I don't see the point of pods unless you are using short manifolds.  Airbox with a K&N filter + an open top (i.e. Ferracci top) is just as efficient to move air.