PCV valve application?

[corey]

So after having completed the pod air filter conversion three years ago, I decided it was time to finally do something with the open end of the crankcase vent tube. A trip to the local Autozone and wah-lah! A generic PCV valve on the end. It's not a little filter like I'd heard people using, but I think it will work.

Anybody else do this before? Seems to be working fine, still have that fumey smell from the case though.. it adds to the "experience."

Let me know if you have had any experience with this mod...

[planedick]

PCV

PCV stands for Polution Control Valve, and it's basically a one way valve so be carefull how you install it. It must be able to exhaust the pressure, but on the other hand it would be nice for it to breath in also because you don't want a vacuum in there either. I wouldn't use it on mine. A little filter would be the best.

[John]

PCV actually means Positive Crankcase Ventilation. It is attached to a Vacuum source on the intake manifold of an engine to draw combustion vapors out of the crankcase, and control the pressure in the crankcase.

[DavesXS]

There will be no vacuum while running. Even with brand new rings. But I agree on not using it though. I'd stick with the little filter.

[trbig]

As stated, you just have to make sure you have it installed correctly, but it is a one way valve and should work just fine. I do know of at least one other member that uses one also...

Different strokes for different folks... More than one way to skin a Kat..


Tod

[Pat Kelly]

Wouldn't plumbing the breather tube (discretely of course) to one of the filters be a good way to go? Maybe a small manifold (aquarium?) that would plumb the main tube to 4 smaller tubes and run those to the 4 nipples we use to sync the carbs.
On Wifes XS750 (sold a couple of years ago) I installed a chrome airfilter box. I installed the 1 into 3 plastic tube the OEM airbox had into the chrome "pod" and hooked the breather tube to that. This way the vapors were burned in the engine as originally intended.
Looked good too.

[geniusloerts]

i run a breather filter on mine

[trbig]

plumb the main tube to 4 smaller tubes and run those to the 4 nipples we use to sync the carbs.

That would cause some lean conditions letting those suck at those points. You could eventually tune for the different air AMOUNT, but the fuel and air get mixed in the carbs, and that would create a stream of just air into the mix.

If you could plumb the line in before the carbs to the filters somehow, that would be the best option, but you'd want to get it to all four somewhat equally, not just one.

[blue giant]

If the PCV valve is indeed a one way valve would it not be possible to create a vacuum in the crankcase when the hot engine cools?

JAT

Paul

[trbig]

No...

Although a piston flying up and down in the cylinder will make compression, there are gaps in the rings that let pressure by. That's why you can hand crank a motor over failry easy. It won't build the pressure up since it slips by the rings. Same thing if there were vacuum built up slowly as the motor cools... it would find a cylinder with an open valve and draw in what it needs.

BUT... this does lead to another "What if"....

PCV valves can get clogged over time. If it got totally clogged, it could get XS pressures built up inside the crankcase... causing???? Blown gaskets?? Oil coming out of strange places?? No telling... just something that you better keep an eye on.

Tod

[81xsproject]

When I had the PVC intake extenders on my bike (before I got the Mikesxs K&N replicas) I had considered plumbing the vents into the extenders. Folks talked me out of it though and I am glad. I have my carbs on and off too much for additional things to disconnect.