Crankcase Breather

[06VMAXIMUS]

Thinking out loud here: I know that with the stage seven and Morley carb kits, that you add a tee into the stock breather and run a hose into the oil fill. The benefit gained is to add extra venting to the crankcase to help with ring sealing. What benefits (if any) would be had to adding this to my bike, which does not have the stage 7 or Morleys kit, but is jetted, K&N'd and piped? Waste of time?:ummm:

 

[dannymax]

Thinking out loud here: I know that with the stage seven and Morley carb kits, that you add a tee into the stock breather and run a hose into the oil fill. The benefit gained is to add extra venting to the crankcase to help with ring sealing. What benefits (if any) would be had to adding this to my bike, which does not have the stage 7 or Morleys kit, but is jetted, K&N'd and piped? Waste of time?:ummm:

Interesting question Bob! :confused2:

 

[hubeerjw]

I think you will get about the same result even without the "upgrades". The more you are able to vent the less restrictions on the engine. I believe (and please don't quote me on this) I have heard that you can get 1-2 extra ponies at the rear wheel by letting the engine vent better. That is very hard to validate since each dyno pull can easily vary that much with no change to the bike itself.

I was talking to a local engine builder (who will be helping me on my dragbike engine) and he is building a mopar competition engine and he is putting an electrical evac. pump on the engine and is hoping to get an extra 7 to 10 HP out of it. We are also talking well into the 600HP range, so it does make a difference.

Jeff

 

[one2dmax]

It will help even a stock engine/carb setup.

 

[Rusty McNeil]

How 'bout a system that uses a hose to the exhaust collector with a check valve fitting, Venturi suction on the engine..

Wonder if that would be overkill.....

I use to do that on some old hot rods, but definetly had to keep an eye on oil consumption

 

[hubeerjw]

How 'bout a system that uses a hose to the exhaust collector with a check valve fitting, Venturi suction on the engine..

Wonder if that would be overkill.....

I use to do that on some old hot rods, but definetly had to keep an eye on oil consumption

I actually did something very similar on my bike... I put an O2 bung in the collector of my Kerker so I could check my A/F levels, and when I'm not, I drilled out an O2 plug and put a piece of pipe in it that the breather hose attached to. It takes a big angle to get the venturi effect going (which I didn't have) and I'm sure it actually creates even more pressure in the cases. I did NOT use a check valve which would help, but just to let you know, my cheap "short-cut" did not work like I had hoped.

Jeff

 

[KJShover]

You guys aren't alone. I had a similar setup on my XS11.

 

[06VMAXIMUS]

Thanks for the replies. Very interesting topic! I remember back when we would go to the drags, seeing the venturi style systems on the headers.

 

[06VMAXIMUS]

OK, I'm still pondering things with another question: So, why is the original crankcase vent insufficient?

 

[one2dmax]

It's not that it's inefficient but there is room for improvement for the guy at home not trying to make his bike meet EPA standards.


Sean

 

[hubeerjw]

It's probably not "insufficient" as much as there is a little room for improvement... just like in the headers, carbs, air filters, etc. There is a balance between cost, realibility, ease of design, manufacture, and assembly, functionality, and of course there are those emmission (and other) requirements that must be met.

I still don't understand why there is such a thing called "porting"... with the technology that is out there. I guess it all has to do with the "all-mighty-dollar"


Jeff

 

[shawnlee]

I installed a hose from crankcase to oil fill and now the bike stumbles upon take off. Is this normal or what? I know my stock carbs are clean and I am puzzled.

 

[wildweasel_pt]

The oil fill goes to the crankcase so i don't understand what you have done. usually the crankcase is connected via the oil fill to the airbox/filterpods to release the pressure on the crankcase.

 

[Bill Seward]

I got really tired of trying to get my big fat hand up under the airbox to connect that damned breather pipe.... After the adventures with the mouse hotel (AKA my air filter), I plugged the little nipple the breather hose attaches to, got a bit of copper tubing bent to the proper angle to run the breather out the left side of the frame. Attached a length of clear hose to the other end of the copper, and ran the plastic tube out and down the side of the frame. It terminates at the level of the shifter. Got a small piece of filter foam, and stuck it into the end of the tubing to keep the engine from inhaling any rocks or crap through the hose. No oil gets out of the end of the hose - in fact, being clear, you can see that no oil is even getting in to the hose. Making up a copy of what I added, I tried blowing through the hose, and noticed no discernable restriction in air flow. Maybe it's not a high-tech solution that gets every last iota of power from the engine, but all I wanted to do was eliminate the PITA of hooking up that hose to the airbox. Success!

 

[Traumahawk]

I actually converted mine to 1/2 inch ful line, plus the T that goes to my oil cap breather. That 1/2 line is so stout, that I can pull the air breather off...and it stays in place, then when I put the air box back on...line it up, and push it back into place. The 1/2 line doesnt give, and it pushes back onto the air box.

 

[johnpclynch]

I got really tired of trying to get my big fat hand up under the airbox to connect that damned breather pipe.... After the adventures with the mouse hotel (AKA my air filter), I plugged the little nipple the breather hose attaches to, got a bit of copper tubing bent to the proper angle to run the breather out the left side of the frame. Attached a length of clear hose to the other end of the copper, and ran the plastic tube out and down the side of the frame. It terminates at the level of the shifter. Got a small piece of filter foam, and stuck it into the end of the tubing to keep the engine from inhaling any rocks or crap through the hose. No oil gets out of the end of the hose - in fact, being clear, you can see that no oil is even getting in to the hose. Making up a copy of what I added, I tried blowing through the hose, and noticed no discernable restriction in air flow. Maybe it's not a high-tech solution that gets every last iota of power from the engine, but all I wanted to do was eliminate the PITA of hooking up that hose to the airbox. Success!

I had the same idea as you except I ran it towards the front of the bike

I've a wide rubber hose running from the breather up towards the Vboost servo where it goes into a decanter, from there I run it down between the front exhausts through a gunk collector and out the left in front of the starter motor to a small chrome air filter (same as the one I put over the drive shaft breather)


My airbox used to collect gunk and eventually block up

 

[Bill Seward]

Could you post a pic of the driveshaft breather?