Crankcase Venting 101

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"Is the use of this check valve going to eliminate the oil from running out on the ground in the probable event of being upside down and pinned by the bike?"

Yes.
 
Bobzilla said:
I know you are supposed to remain wheels down but I am working on my freestyle tricks and am in the process of doing a jump where I stay upside down for extended periods of time and the only thing holding me back is the loss of oil. :twisted:
Click to expand...

8O I hope to witness a demonstration of this "freestyle trick" in the near future. :lol:



Log
 
LINEAWEAVER said:
Gentlemen,

Dry crank singles (those already equipped with a reed valve crankcase) benefit from the additional check valve only with regard to oil containment.

Many OEM singles employ a pulse air system which draws from the inlet box. In opposition to deactivating said system (common practice) I often simply replace the air box tap with that of the crankcase spigot.

The majority of OEM multi cylinder street bike engines are also equipped with such a system. I once again take advantage by routing the crankcase vent to the scavenging inlet.

A vacuum in the crankcase reduces pumping losses and improves ring seal. (a result of increased pressure delta above and below the piston and ring assembly)

I would like to take credit, however, such is old school technology and has been around since the sixties.

I am indeed beginning to realize that unlike crankcase scavenging many of you have not been around since the sixties and therefore much of what I have to say comes across as brilliant. Some content is indeed brilliant, however, I cannot take credit for that which is not my own.

Kind Regards,
Dale

Reprint:
Concept: Apply a vacuum to the crankcase. Rather than putting a breather on the valve cover to let pressure out, actually suck the air out to create a vacuum.

Benefits of Crankcase Evacuation:

1) Cleans up installation (prevents oil leaks from crankcase sources)

2) Reduces parasitic losses from pistons pumping air

3) Improves ring seal

4) Increases HP by 4-7% depending on the application

5) Eliminates PCV and possibility of oil being sucked into intake system

Tech / Method:
Basically seal the crankcase and run a line from the crankcase to an air pump (or other source of vacuum) and from the air pump to a breather tank. Additionally, if necessary, use a vacuum relief valve to ensure vacuum does not get too great. If you put more than 12in vacuum on the crankcase, you can suck the oil off the front and rear main bearings. That would be a bad thing. Alternatively, with the crankcase sealed up tight to achieve good vacuum, you don't want your pump failing either which would allow a severe buildup of pressure in the crankcase then.

Typically, crankcase evacuation systems employ either a "race type" belt-driven pump or use exhaust as a source for vacuum. Both of those can have problems for street application. The belt-driven pumps are almost always specified for full race applications and therefore would need rebuilt every few thousand miles. If you use the exhaust as a source for vacuum and you have mufflers, you may end up with a buildup of oil in your exhaust ahead of the mufflers. Electric pumps can be used but our experience was they are problematic and don't produce enough vacuum.
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Hi Dale,

I have three questions: #1 How many psi is 12inches of vacuum? and #2 In another post you stated the valve you made would be too expensive to sell, you reccomended an automotive valve, and one of the posts listed in the this thread listed the ET performance valve for large v twins. With the current rocker box design of the Husaberg's with two vents into one then into the frame, would one of these et vents, or the cheaper automotive vent that you mentioned work if the two vents are "Yed" into one and then into the valve? #3 Is there a concern of having enough vacuum to pull dirt through the weep past the water pump bearing seal into said bearing and the engine?
 
How many psi is 12inches of vacuum?
12 inches of water is roughly .4 PSI absolute.
12 inches of Mercury is roughly 6 PSI absolute.

In another post you stated the valve you made would be too expensive to sell, you reccomended an automotive valve, and one of the posts listed in the this thread listed the ET performance valve for large v twins. With the current rocker box design of the Husaberg's with two vents into one then into the frame, would one of these et vents, or the cheaper automotive vent that you mentioned work if the two vents are "Yed" into one and then into the valve?

I am not a big advocate of aftermarket "Harley Davidson" crank vents. Most any oil resistant, fast acting valve will suffice.


Is there a concern of having enough vacuum to pull dirt through the weep past the water pump bearing seal into said bearing and the engine?

No.
 
Smorgasbord said:
How many PSI absolute is atmospheric pressure? Or inches Hg. Or inches H2O?
Click to expand...

Depending on altitude and temperature roughly 14.7 PSI.
 
LINEAWEAVER said:
How many psi is 12inches of vacuum?
12 inches of water is roughly .4 PSI absolute.
12 inches of Mercury is roughly 6 PSI absolute.

In another post you stated the valve you made would be too expensive to sell, you reccomended an automotive valve, and one of the posts listed in the this thread listed the ET performance valve for large v twins. With the current rocker box design of the Husaberg's with two vents into one then into the frame, would one of these et vents, or the cheaper automotive vent that you mentioned work if the two vents are "Yed" into one and then into the valve?

I am not a big advocate of aftermarket "Harley Davidson" crank vents. Most any oil resistant, fast acting valve will suffice.


Is there a concern of having enough vacuum to pull dirt through the weep past the water pump bearing seal into said bearing and the engine?

No.
Click to expand...

Thank You Dale.
 
ET Performance makes the valves not only for the Harleys but to fit in the hose & for automotive applications also. I had one on my 525 KTM & it pulled about 4-5". Simple to install, just cut the breather hose & insert. I have one on my 'Berg but haven't put the gauge on it. Also running them on my drag Ranchero & they seem to last, the automotive ones I had on my Ranchero didn't.
 
RE: Re: Crankcase Venting 101

Anyone know of a supplier or part number for a check valve available in the UK? Taffy....?......:)
 
Just curious here. Would it be that horsepower gains may be had when applying vacuum to the crankcases because a vacuum under the piston helps to pull it down the stroke and as the piston rises vacuum underneath also increases ? In the case of the Berg would it help if a seperate valve or hole was tapped directly into the crankcase (not the gearbox) and then taken to exhaust vacuum along with a breather from the rocker cover. The two could be joined wit a Y piece then go through the one way valve and then to vacuum.

Just thinking out loud here, wouldn't the effect be the same with vacuum just going through the rocker cover as the reed valve would act as a one way valve ?
Cheers Dan
 
Can anyone recommend any more part numbers for cheap check valves that work well for the Crankcase Vent mod?
 
Thanks Smorgasbord, that one is cheap! The only problem is, it wouldn't allow me to connect a hose to the other side, as I'd like to connect the other end of the valve back to the frame.

I use the bike for supermoto and street, so I don't want oil vapor blowing around at all, as it may end up on the rear tire.

I'm looking for a vehicle year, make and model of car or truck (in North America) that has a check valve that works well on the berg, so I can go and pick one up at the parts store after work today.

Thanks
 
Air Injection Check Valve (Jaguar # C34017) All XJS with V12
(Note: This is a GM part. It is used, for example on a 350 cu inch Chevrolet V8.
A1 Cardone A42-103
AC Delco 2332530
Automotive Electronics 17001
Big A 46-1005
Borg Warner CV8
Filko 45-105
GP Sorenson / Guaranteed Parts 779-2929
Kem 174-176
Motormite 55050
NAPA 2-2900
Niehoff FE-476
Sound Solution 15903
Standard / Carquest AV7
Tomco Ellis 17001
Walker 15903
 
negative pressure in crankcase - not so good

a similar mod when done in a gsxr 1k may cause it to blow an oil seal.. The seals weren't designed to withstand that kind of abuse....

You may search for 'vacuum mod' in google etc.... Just remember that excess negative pressure in the crankcase might have (tiny if any) benefits performance wise but may cause your oil seals to fail etc....

I don't know if that's the case with bergs as well, but i thought it would be a good idea to tell you what i know....
 
well after going to all the auto part retailers and garages in my area and being met with confused looks i ordered a high speed check valve from the states, not the kem one recommended by dale but the same from another manufacturer.

$30 all in plus it arrived in 3 days. which is something considering post isnt usually that fast within the uk!

023_G.sized.jpg


have been running an open breather pipe for a little while but have gotten a little paranoid about it sucking up water which is rather odd as i've never had a bike suck water up the header breater, plus the oil vapour reacting with the water and making the lower frame rails and ignition cover oily white was annoying me.

the rearward vent and the airnox vent are capped with 19mm walking stick tip rubbers. fitted perfectly.

there is also about 6 mm clearance between the valve and the rad despite it not looking that way.

anyway been for a spin and all seems well. bike seems smoother and stronger but think that's just my imagination.
 
HeyJohnnyPark said:
Im going to be using my bike for Street Use Only, why would this be need to do a crank vent mod?
Click to expand...

no need at all.

no need for me to do it other than i could and wanted to try it plus i've had the carb fill with oil a couple of times following crashes and its a pain in the ass.

doing this is an easier way of preventing that than not crashing.
 
HeyJohnnyPark said:
Im going to be using my bike for Street Use Only, why would this be need to do a crank vent mod?
Click to expand...

Other than a potentially slight H.P. increase the chances of flipping the bike over on the street and having the crankcase fill the cylinder with oil are quite slim. Off road the chances tend to increase and a breather mod is not a bad idea.
 

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