Crankcase evacuation valve

Started by Colorado700R, June 09, 2008, 11:15:54 AM

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Kenny

  Okay, here is my best explanation; When the piston comes to bottom dead center, the crankcase will be at max pressure. This pressure bleeds out through the valve. The valve will slam shut, trapping vacuum as the piston goes back up. This stabilizes the rings and improves seal. The valve is extremely sensitive and durable. I have a guy build these for me that actually has a patent on them. They withstand nitromethane and methanol. I just happened to be in the right place, at the right time when I found these badboys :grin_nod:
KDS Racing
685 Hope Rd
Floyd VA 24091
NEW PHONE 540-818-9154
Paypal: kenny@swva.net

:satan:

socalrappy700

Thanks for the pics and write up Kenny.  You have been helpful as always.
07 SE2

~Erich


Yamaha Raptor Forum

Colorado700R

Money enroute for Dylthiium Crystals  I mean cam cover evacuator valve  :thumbs:

:grin_nod:

ThisGuyAlex

so it's a pcv valve from a car basically?
sold the raptor....full on 05 yfz in progress...

stock parts: fuel tank, swingarm and rear shock

Kenny

KDS Racing
685 Hope Rd
Floyd VA 24091
NEW PHONE 540-818-9154
Paypal: kenny@swva.net

:satan:

Krandall

#20
question..

when the valve releases the pressure while the piston is at bottom and the piston goes back up. How does the crank case get more air? Wouldn't the piston on the way back up try to pull air in? If it's not coming through the valve, is it pulling it through the rings?

Or am I missing something?


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preddy08

Quote from: Krandall on June 16, 2008, 12:39:04 PM
question..

when the valve releases the pressure while the piston is at bottom and the piston goes back up. How does the crank case get more air? Wouldn't the piston on the way back up try to pull air in? If it's not coming through the valve, is it pulling it through the rings?

Or am I missing something?

The crankcase does'nt get more air, thats what makes it work. When the piston goes up in its stroke it creates a vacume and forces the rings outward for a more positive seal.
Just a little 81hp trail bike.


Krandall

Quote from: preddy08 on June 16, 2008, 12:55:56 PM
Quote from: Krandall on June 16, 2008, 12:39:04 PM
question..

when the valve releases the pressure while the piston is at bottom and the piston goes back up. How does the crank case get more air? Wouldn't the piston on the way back up try to pull air in? If it's not coming through the valve, is it pulling it through the rings?

Or am I missing something?

The crankcase does'nt get more air, thats what makes it work. When the piston goes up in its stroke it creates a vacume and forces the rings outward for a more positive seal.

So how does more air get in the crank? seepage past the rings? This thing obviously lets out more air than just 1 puff right?
Sorry if I'm coming across as a noob. I'm learning ;)


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preddy08

Quote from: Krandall on June 16, 2008, 12:58:27 PM
Quote from: preddy08 on June 16, 2008, 12:55:56 PM
Quote from: Krandall on June 16, 2008, 12:39:04 PM
question..

when the valve releases the pressure while the piston is at bottom and the piston goes back up. How does the crank case get more air? Wouldn't the piston on the way back up try to pull air in? If it's not coming through the valve, is it pulling it through the rings?

Or am I missing something?

The crankcase does'nt get more air, thats what makes it work. When the piston goes up in its stroke it creates a vacume and forces the rings outward for a more positive seal.

So how does more air get in the crank? seepage past the rings? This thing obviously lets out more air than just 1 puff right?
Sorry if I'm coming across as a noob. I'm learning ;)

Thats the beauty of this valve, is that there is NO "air" in the crankcase on an upward stroke.
Just a little 81hp trail bike.


Krandall

Quote from: preddy08 on June 16, 2008, 01:06:16 PM
Quote from: Krandall on June 16, 2008, 12:58:27 PM
Quote from: preddy08 on June 16, 2008, 12:55:56 PM
Quote from: Krandall on June 16, 2008, 12:39:04 PM
question..

when the valve releases the pressure while the piston is at bottom and the piston goes back up. How does the crank case get more air? Wouldn't the piston on the way back up try to pull air in? If it's not coming through the valve, is it pulling it through the rings?

Or am I missing something?

The crankcase does'nt get more air, thats what makes it work. When the piston goes up in its stroke it creates a vacume and forces the rings outward for a more positive seal.

So how does more air get in the crank? seepage past the rings? This thing obviously lets out more air than just 1 puff right?
Sorry if I'm coming across as a noob. I'm learning ;)

Thats the beauty of this valve, is that there is NO "air" in the crankcase on an upward stroke.


I get that part
Why not just warm up the motor, move the piston to where it's all the way down (farthest it can go down) and then seal the crank exhaust hole?


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preddy08

Quote from: Krandall on June 16, 2008, 01:10:17 PM
Quote from: preddy08 on June 16, 2008, 01:06:16 PM
Quote from: Krandall on June 16, 2008, 12:58:27 PM
Quote from: preddy08 on June 16, 2008, 12:55:56 PM
Quote from: Krandall on June 16, 2008, 12:39:04 PM
question..

when the valve releases the pressure while the piston is at bottom and the piston goes back up. How does the crank case get more air? Wouldn't the piston on the way back up try to pull air in? If it's not coming through the valve, is it pulling it through the rings?

Or am I missing something?

The crankcase does'nt get more air, thats what makes it work. When the piston goes up in its stroke it creates a vacume and forces the rings outward for a more positive seal.

So how does more air get in the crank? seepage past the rings? This thing obviously lets out more air than just 1 puff right?
Sorry if I'm coming across as a noob. I'm learning ;)

Thats the beauty of this valve, is that there is NO "air" in the crankcase on an upward stroke.


I get that part
Why not just warm up the motor, move the piston to where it's all the way down (farthest it can go down) and then seal the crank exhaust hole?

That is kinda what its doing, but its doing it every revolution. Air will bleed off from the rings and from other misc area. So if you do it once it may last 30 seconds, this valve does it every storke.
Just a little 81hp trail bike.


Krandall

I gotcha. It sorta makes sense.. It makes the most sense on the up stroke creating the vaccum making a better seal. But what's wrong with just letting it breathe like it is set up stock?  I mean sure you don't get the vaccum, but it'd be letting out the pressure just the same correct?


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preddy08

Quote from: Krandall on June 16, 2008, 02:00:52 PM
I gotcha. It sorta makes sense.. It makes the most sense on the up stroke creating the vaccum making a better seal. But what's wrong with just letting it breathe like it is set up stock?  I mean sure you don't get the vaccum, but it'd be letting out the pressure just the same correct?

Someone eles said expained it as if you were to put a brick and a feather in a jar and suck all the air out of it. They would both fall at the same rate. Its all about resistance.

As it is set up stock, it sucks and blows with every stroke :rofl: :rofl: get your mind out of the gutter, that is the best way to describe it.
Just a little 81hp trail bike.


Krandall

hmm, wouldn't there be more resistance though with the valve then? because with the piston going up, it's creating a vacuum which would create more resistance on the piston moving upward correct?



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preddy08

Quote from: Krandall on June 16, 2008, 02:43:53 PM
hmm, wouldn't there be more resistance though with the valve then? because with the piston going up, it's creating a vacuum which would create more resistance on the piston moving upward correct?



Correct, but the vacum created is GREATLY overcame by the force of the motor.
Just a little 81hp trail bike.