Author Topic: Crankcase breather - K&N Vents  (Read 5423 times)

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Machismo

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on: August 15, 2012, 08:00:46 pm
Has anyone tried this custom breather box?
http://www.bikebandit.com/k-n-1-piece-crankcase-vents

There are far too many threads and talks on the removal/alteration of stock breathers.
Some say the vent on the timing chest, if blocked, will result in a performance degrade.
Others just suggest blocking PAV line and the one from primary.

I have blocked the primary/PAV and disconnected the pipe from catch can to the airbox.
Sorry for chewing the same gum again, but its the quest to know what's the best thing to do.

Cheers
Sudhir


Philbomoog

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Reply #1 on: August 16, 2012, 10:45:47 am
 There will be liquid gunk coming from the breather, which is why they are fitted with a catch can. Its not ideal but the gunk needs to go somewhere. That device looks like a filter which would just get blocked up with gunk as stop working fairly quickly.

There's lots of options available on the forum if you've got a bit of time to search for catch can or breather mods.


Machismo

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Reply #2 on: August 16, 2012, 03:54:18 pm
Thanks Philbomoog..
But the question that is bothering me more is, would blocking the vent on the timing chest degrade the bike's performance.


AVL Power!

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Reply #3 on: August 16, 2012, 04:11:00 pm
Vent in timing chest? Can you post a pic? I am soo confused! :o


Philbomoog

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Reply #4 on: August 16, 2012, 04:50:08 pm
There's been some discussion before about the 'vent' on the timing side. It was originally connected to the catch can, as was a similar one from the primary. There were differing opinions about its function. Is it a vent from the timing case, a drain into the timing case, I don't think there ever was a final answer.

Some people have blocked theirs off, others have kept the catch can.

I connected a hose between the primary and the timing case. Its been on there for 10000 miles and is bone dry inside, with no trace of residue. I don't think either of the vents are doing anything. Certainly no effect on performance. I did post a picture but I can't find it.


tooseevee

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Reply #5 on: August 16, 2012, 05:00:34 pm
Vent in timing chest? Can you post a pic? I am soo confused! :o

            AVLs have a vented timing chest with a plastic hose that is a RETURN line from the catch can to drain excess oil from the catch can back to the engine if the level rises above a certain level in the catch can. If the catch can is done away with & the crankcase vent is vented to the atmosphere, there is no reason for the timing case fitting not to be plugged off or closed or whatever. Nothing is going to "come out" of it.

             Machismo: 
             Closing this vent has nothing to do with power or loss of power or anything. It has nothing to do with the bike's performance. That line is to save the random drop of oil getting on the street once in a while.

              This mostly doesn't work anyway. The excess usually ends up being sucked into the air cleaner & clogging IT up & then dripping out through the hinge of the air filter case & onto the muffler. And the street.
RI USA '08 Black AVL Classic.9.8:1 ACEhead/manifold/canister. TM32/Open bottle/hot tube removed. Pertronix Coil. Fed mandates removed. Gr.TCI. Bobber seat. Battery in right side case. Decomp&all doodads removed. '30s Lucas taillight/7" visored headlight. Much blackout & wire/electrical upgrades.


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Reply #6 on: August 16, 2012, 06:27:52 pm
Catch Can - That's located right under the seat? has 2 pipes connected to that thing? which also holds used engine oil? and often leaks? :P


Machismo

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Reply #7 on: August 16, 2012, 06:34:21 pm
tooseevee, well i certainly hope it doesn't matter - but i do remember reading somewhere here that it's gonna affect adversely. Good to hear it doesn't.
I already blocked the air box end to protect it from puking into the box.

dampking - yes, thats the one. It has four outlets - one from crank case, primary, timing and one to the airbox.
You got to clean it whenever it leaks.


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Reply #8 on: August 16, 2012, 10:23:49 pm
Do we really need that thing? it's really messy!


tooseevee

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Reply #9 on: August 17, 2012, 01:10:12 am
Do we really need that thing? it's really messy!

              No, you don't need it & there's been a lot, a lot, written about how to deal with it.
RI USA '08 Black AVL Classic.9.8:1 ACEhead/manifold/canister. TM32/Open bottle/hot tube removed. Pertronix Coil. Fed mandates removed. Gr.TCI. Bobber seat. Battery in right side case. Decomp&all doodads removed. '30s Lucas taillight/7" visored headlight. Much blackout & wire/electrical upgrades.


tooseevee

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Reply #10 on: August 17, 2012, 01:21:11 am
tooseevee, well i certainly hope it doesn't matter - but i do remember reading somewhere here that it's gonna affect adversely. Good to hear it doesn't.


            Well then, don't just take MY word for it. I'd like to know myself.

             I just can't see how blocking off a tube that has no suction OR pressure on it could effect anything & I've seen no effect one way or the other from plugging mine.

              Nothing vents out of the primary case vent either.
RI USA '08 Black AVL Classic.9.8:1 ACEhead/manifold/canister. TM32/Open bottle/hot tube removed. Pertronix Coil. Fed mandates removed. Gr.TCI. Bobber seat. Battery in right side case. Decomp&all doodads removed. '30s Lucas taillight/7" visored headlight. Much blackout & wire/electrical upgrades.


Machismo

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Reply #11 on: August 17, 2012, 01:30:27 am
                         I just can't see how blocking off a tube that has no suction OR pressure on it could effect anything & I've seen no effect one way or the other from plugging mine.
The timing side vent does have a suction. I have noticed it while experimenting with the blocking/unblocking.


ace.cafe

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Reply #12 on: August 17, 2012, 12:33:29 pm
The timing side vent does have a suction. I have noticed it while experimenting with the blocking/unblocking.

If the engine is running, and air is being expelled out the main breather hose by the piston action, then ANY open hole that connects anywhere to the crankcase is going to have a "suction". That doesn't mean it's needed.
As others have mentioned, it is merely a return line for excess oil expelled out the breather, that gets into the catch can. It's basically just a part of the pollution control requirements.

I can assure you that the Iron Barrel predecessor Bullets ran quite normally for 50 years without any of that nonsense on them.

Regarding any "filters" on the breather, the breathers are not intended to take any air in. They are intended to ONLY blow air out via the main breather hose which has a duckbill ONE-WAY valve on the end to PREVENT any air from coming back in.
Attempting to add an air inlet somewhere does nothing but circumvent the breathing system of the engine, and adds to unwanted pumping losses which lose horsepower.
« Last Edit: August 17, 2012, 12:36:50 pm by ace.cafe »
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Machismo

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Reply #13 on: August 18, 2012, 07:05:58 pm
That was informative Ace. Thanks..
Yeah, the arrangement in the older CIs are damn simple and effective. Someday, I might just chuck this can and go for the old arrangement!