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Discussion Starter #1
Just spit ballin here, but I am curious as to the reason for the crankcase vent on EVOs just running to the ground. What is the downside of running it back to the bag? I have read of catch cans and so on, so there must be a reason. I just don't like cleaning up the mess. it doesn't do it all the time unless it sits for a good while, wet sumping I suppose.

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Fire it up once a week and forget about messing with the vent.

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Would there be enough pressure to push the oil up-hill and keep the vent hose clear?
Or would it accumulate at the low point?
 

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Would there be enough pressure to push the oil up-hill and keep the vent hose clear?
Or would it accumulate at the low point?
The stock configuration runs as high as the carburetor intake, so I don't see that as an issue. I'm guessing HD didn't want crankcase pressure interfering negatively with the function of the oiling system, but I haven't studied it enough to speak intelligently about it.
 

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Discussion Starter #7
I keep a pan under it, I just don't want to oil up someones driveway, again.

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And then drain back into the engine when sitting again.
HaHa! I guess that wouldn't be the worst thing, eh?

The stock configuration runs as high as the carburetor intake, so I don't see that as an issue. I'm guessing HD didn't want crankcase pressure interfering negatively with the function of the oiling system, but I haven't studied it enough to speak intelligently about it.
Do you think it would?
Isn't the oil tank vented? So if the vent tube was above the oil level and just dripped down, would there be so much pressure that it would interfere with oiling system function?
Also I seem to remember something (from Thermodyne?) that an engine can have excessive crankcase pressure when it needs a rebuild... or something like that. haha! I'm not much help.
 

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Discussion Starter #9
I am going to pull the heads and jugs for a refresh and inspection over the winter. the engine has almost 42K on it but runs like a champ. It needs some new gaskets and seals, it's 28 years young. I will look at the vent plumbing then.

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I'm thinking I wouldn't vent to the tank or real long uphill hose because part of the gases vented is water vapor, especially in humid climates. All engines condensate when sitting. You don't want to recapture water.
 
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