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Crankcase Venting

You would never just want to vent a crankcase breather tube without having the negative pressure as Glider suggests. You want a system that creates or simulates PVC or positive crankcase ventilation. (it's called "positive" but it really is not. It is being compared to an absolute zero environment of pressure. Remember what we call "Zero" here on the planet is not zero at all. It is 14.7 psi.)

You WANT to pull or extract & remove crankcase piston blow-by fumes out of the crankcase. Not for a horsepower gain but to remove/prevent crankcase sludge forming fumes. A PVC valve is not just a "one way valve" . It is a very calibrated device that must be connected to a source of vacuum.

What you want to have is the crankcase tube under a slight pressure that is below atmosphere pressure at all times. Something under atmospheric 14.7 psi. An easy way to do that is by doing what Glider suggested earlier.

Remember the old "draft tubes" on cages back in the 50's and 60's before PVC was developed.?
It worked because of the venturi effect but ONLY when the car was in motion. By just letting the tube hang below the engine, your not even getting the venturi action on the tube like they did 50 years ago.

Never, just leave a breather tube hanging low below an engine without any means of creating a low pressure vacuum applied to it.
 
as glider say's ,,creating negitive pressure allows pistons to move freely,, but it also allows unburned hydrocarbons (gas) to reintroduced into the combustion chamber .. less h/c's in the air mean's less smog
 
Well he went with the Hayden and it's installed. Seems to sound a little tighter and he says it's got a little more response. Now his prime objective is to clean up the mess underneath the bike. Gave him a bottle of Bike Brite!!!
 
90FXRS said:
Well he went with the Hayden and it's installed. Seems to sound a little tighter and he says it's got a little more response. Now his prime objective is to clean up the mess underneath the bike. Gave him a bottle of Bike Brite!!!
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Didnt early model FXR have the oil filter under the tranny, seems to me some of these filter mounts would loosen up over time ?
 
rlb333333 said:
as glider say's ,,creating negitive pressure allows pistons to move freely,, but it also allows unburned hydrocarbons (gas) to reintroduced into the combustion chamber .. less h/c's in the air mean's less smog
Click to expand...

PCV is fundamental method to get rid of the dripping "draft tube" Hoop referred to here in California in 1965...:small3d007: Glider knows what he is talking about. "Positive Crankcase Ventilation" actually a misnomer, a slight vacuum (negative pressure) from carb side connection will draw oil and moisture laden vapors to help relieve trapped air in the crankcase preventing oil/air pumping.

Keeping those vapors from venting into the atmosphere or trapped moisture laden crankcase area by drawing out water condensation from sitting in your garage at startup.
 
If the cranckcase did not vent we would have a bigger mess of oil to mark our spot, plus as Glider and NEWHD said the excess unburned gases get recycled before exhausting saving the ozone and saving the engine from too much pressure:s
 
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