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Crankcase Venting 101

LINEAWEAVER

LINEAWEAVER

Joined Jul 2001
3K Posts | 1+
El Sobrante, Ca. 94803
Hello friends,
For what it may be worth:

If one can insure a slight crankcase vacuum (in particularly regarding a large displacement single) power shall increase coupled with a reduction in oil spewing. Such technology is certainly not new as it has been used by the drag racing community for many, many years. Simply look to the nineteen sixties era blown altereds with their exhaust scavenged crankcases.

On many a fours cycle engine (including Harley Davidson Big Twins and Rotax Singles) I have placed a high speed one-way check valve in the crankcase vent line. Doing such has proven true to form for some two decades now. (As a matter of fact their are over the counter CNC pieces now available through most HD speed merchants.)

Regarding the Husaberg engine:
Power output did not improve using such a device primarily as a result of the OEM crankcase reed valve. However, If a reduction of oil spewing is your primary objective an auxiliary check valve could be just what the doctor ordered.

An automotive air pump check valve serves the purpose nicely @ a fraction of the HD cost. One may purchase KEM part number 174-176 or cross reference said number to that of your local automotive vendors inventory (Kragen, etc.) .

Hope this helps.

Sincerely,
Dale
 
Dale thanks for the part number. Is the reason Husaberg routes the breather to the air intake an emissions issue or to possibly help pull the pressure from the crankcase? or maybe not to waste good Delo 400 :D

Thanks,

Eric
 
Question:Are you referring to a PVC valve?If that is what it is;then that would make things a lot easier.Thanks for the information.
 
wildbill said:
Question:Are you referring to a PVC valve?If that is what it is;then that would make things a lot easier.Thanks for the information.
Click to expand...

Hi Bill,
No, it is not a Positive Crankcase Ventilation valve.

Most late model automotive engines rely on some form of fresh air exhaust induction to lower emission levels. Such a system requires a high speed check valve. The supplied part number is such a valve for several GM automobiles.

Kind Regards,
Dale
 
Thanks Dale for clearing that up.I will check on that and see what I can come up with.Thanks for the part numbers to because my local auto parts guy is slow but he gets it right and that is all that matters.
 
Dale:

When using the air pump check valve does the lack of air being able to flow back into the motor have any consequence? Most breather mods done to other motors use a filter, K&N or equivalent, citing that this will allow air to flow back into the motor during deceleration and cooling off.
 
Although of no consequence crankcase vacuum will slowly diminish once the engine has been shut down.

Kind Regards,
Dale
 
Received my air pump check valve today. It seems that most if not all of the OEM cross reference part numbers are wrong on the KEM web site. I got mine from a Chrysler dealer. Part number is 04300376 and cost is about $30. Just need to scrounge up an adapter for the female threaded end and a slick way to close the frame opening.
 
The female end of the valve should be that of a standard pipe thread and a 5/8" spigot coupled to the appropriate male pipe end should be quite easy to fashion. I would suggest you then top off the complete assembly with a small K&N breather filter.

The frame spigot is easily blocked using a suitable cap such as that used to plug automotive heater line spigots.

Hope this helps.

Sincerely,
Dale
 
I got mine today, but it's not PolyVinyl Chloride ... I'm gonna return it.


:lol: :lol: :lol:


~ Ken
 
I mounted the one way valve with 3/4'' automotive heater hose between the head and valve. A 3/4" to 5/8"bass fitting sourced at Home Depot screws into the valve. 5/8" heater hose is then used for the rest of the routing.
Breather%201



I looped the 5/8" hose up and over the frame backbone.
Breather%203



Its a tight fit between the radiator and tank. 3/4" (19mm) would be too big. 5/8" is good.
Breather%204



Zip tie hell, I know. Should blow right on the chain. We will see.
Breather%205
 
The super spiffy,cool 8) , BOSS radiator guards are for the 05. The bike pictured here is my 01 470.

Congratulations on the win!
 
when I put one of these on my xr600 crank vent it perked up considerable.
Probably work good on an 883 too.
 
SFO said:
when I put one of these on my xr600 crank vent it perked up considerable.
Probably work good on an 883 too.
Click to expand...

Said valve does indeed work quite well on the Harley Davidson V2 hence my first ever encounter using such a device. Big twins have considerable trouble regarding sumping during prolonged high rpm operation. (ie Mile Dirttrack) :D

Now stop letting all my cats out of the bag! :D

See ya soon SFO.

Dale
 
SFO said:
Super sorry Dale.
Since you were advertising said valve I got excited.
Click to expand...

I was just kidding!
:D LOL

Somewhere around here I have pictures of an 883 of which I used four Husaberg reed valves to vent the sump into the primary.
 
oil, oil everywhere!

On my 98 600 I ran a hose from the breather over the tank and down the other side with a filter on the end.Cheap fix,I thought,after some High speed dual sporting this weekend I was amazed How much oil comes out!Is this normal!The whole side of the motor and boot was covered in oil.Checking the oil at a gas stop showed me to be about 1/2 a quart low!I plan on changing to Dale's check valve system ,my question is how much blow by or pressure is normal or do I need to look at something else?
 

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