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· Registered
Rebel 250 1996 second gen
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38 Posts
Discussion Starter · #1 ·
Hey guys!! I was messing with my bike and I noticed that the separator has broken from the years and I was thinking about removing the crackcase ventilation system all together and replace it with a hose that runs under the engine... (Not a filter since they clog easily) I have been reading on the forums for days and I have seen some pretty good solutions on buying a catchcan and reroute it to the pod filter but I get why to do that? Except from the emissions and environmental reasons, is there any other use for this system? I have read that the connection to the filter give the crackcase a positive ventilation system but why is this better than a free flow hose under the bike, since the crackcase will still breath and have an opening...
 

· Administrator
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5,104 Posts
Air flows in and out of the breather at a significant volume so whatever is in the air that's being drawn back in is going to be in your crankcase.

Dust, bugs, water, etc.
 

· Registered
Rebel 250 1996 second gen
Joined
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38 Posts
Discussion Starter · #3 ·
Air flows in and out of the breather at a significant volume so whatever is in the air that's being drawn back in is going to be in your crankcase.

Dust, bugs, water, etc.
Oh! So the crackcase also gets air in? Now I get it! Will a catch can with a filter on top work? Btw some guys are rerouting the hose before the pod filter and other guys after on a PVC pipe! Which one is better?
 

· Super Moderator
1987 CMX250C AC
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3,762 Posts
Both pistons move up and down at the same time..
When they move up 200+cc of atmosphere is sucked into crankcase, than crankcase is purged as both pistons return to BDC

math wasn't my forte, but as I figure it 5000 rpm x 200cc = 1,000,000cc of air being pumped in and out of crankcase every minute..

ok ok so those figures are off due to ability of air to be compressed, still a lot of sucking & blowing..

Honda devised a crankcase ventilation oil catch can (we call the puke tube) with the oil separator drain, being connected to carb intake which helps with scavenging vapor out of hose

plumb a catch can with an attached filter in any manner you wish..
could even build catch can out of PVC

More likelihood of moisture and/or oil vapor to condense inside plumbing the longer or more complex it is..
 

· Premium Member
1987 rebel 2004 sportster
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503 Posts
Before there was a positive crank case ventilation system on cars(AKA the PCV system )there was an empty tube that ventilated the engine. It was called a road draft tube. I don’t know why that was just an open tube and the puke tube is plugged. This is why I seldom deviate from stock setups. I am not smart enough to out-engineer the engineers:unsure: I do admire those that have the moxie to try!
 
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