Topic: so i have a K&N filter for cb550; hose route?

[xsmooth69x]

so i have a K&N air filter for my cb550 but now im confused on how to hook up the breather tube.

if i remember before i took everything apart the hose went from the bottom of the stock airbox to the top of the engine breather thing.

now on my K&N i have a section where i can put that hose on and then run it to the engine breather.

so how do i do this? which one do i pick?

[caluser2000]

Top to top (2).  I take it (1) is the vent on the rh side. On my 550F the breather connects to the a fitting in the centre of carb collector box between the two centre carbs.

[xsmooth69x]

Top to top (2).  On my 550F the breather connects to the a fitting in the centre of carb collector box between the two centre carbs.

ya mines just a regular 550 so my air box doesn't have that and instead has it on the bottom.

so since i dont use the bottom outlet to i just put a cap on it or something?

[caluser2000]

I'd fit a hose, place it somewhere discrete with a small filter attached.

[xsmooth69x]

I'd fit a hose, place it somewhere discrete with a small filter attached.

well i could just fit a filter right over it outlet

[caluser2000]

Yes you could.

[dave500]

but you shouldnt,,set it up like a 500,just let the open end of the hose hang down,you might need to make it longer,dont put anything over the outlet,it should hang down and catch the breeze so fumes are siphoned off,like old pre pcv valve cars.

[TwoTired]

#2 is the answer.

The plenum box lower fitting is a drain in the event that carbs overflow and try to pool raw gas in that plenum.  That would be bad.  Potential flambe`.

The original drain tube is a reduced diameter molded type.  The reduced diameter restricts the amount of air that can bypass the air filter.  Also the end of the tube had some open cell foam stuffed in it, to keep critters from venturing into an inviting dark hole for nest building.

Cheers,

[Duanob]

I cut off the sipping end of an old Camelback bladder tube and fixed it as a drain. Then routed it down between the motor and the rear tire. Then every now and then squeeze the nipple to drain the excess water and crud onto a cloth or paper towel. I haven't had anything come out yet.

[xsmooth69x]

ya i actually have one of those coveted rare nipple split squeeze tube thing that fits at the end of that tube. so is that drain tube like a 1/4" tube?

[TwoTired]

I cut off the sipping end of an old Camelback bladder tube and fixed it as a drain. Then routed it down between the motor and the rear tire. Then every now and then squeeze the nipple to drain the excess water and crud onto a cloth or paper towel. I haven't had anything come out yet.

Sorry, you are confusing the stock air filter box breather system drain with the plenum overflow drain.  These serve two different functions.
The bladder tube you describe would still allow gas to pool in the plenum chamber.  The pinch tube is the correct function for the filter box drain only, not the plenum chamber.
The K&N setup will route all the water condensate and other vapors/gasses to the combustion chamber, to be burned there.

Cheers,

[TwoTired]

so is that drain tube like a 1/4" tube?

Yes .  I think in necks down to that or maybe even a little smaller.  If you think of it's purpose, it ought to be the same size as the fuel inlet diameter to the carbs, so fuel can flow out of the plenum/now cistern as fast as fuel can come in from the gas tank.

Cheers,

[xsmooth69x]

so is that drain tube like a 1/4" tube?

Yes .  I think in necks down to that or maybe even a little smaller.  If you think of it's purpose, it ought to be the same size as the fuel inlet diameter to the carbs, so fuel can flow out of the plenum/now cistern as fast as fuel can come in from the gas tank.

Cheers,

perfect thanks twotired

[Duanob]

ya i actually have one of those coveted rare nipple split squeeze tube thing that fits at the end of that tube. so is that drain tube like a 1/4" tube?

they're made of unobtainium, cherish it!

[Duanob]

I cut off the sipping end of an old Camelback bladder tube and fixed it as a drain. Then routed it down between the motor and the rear tire. Then every now and then squeeze the nipple to drain the excess water and crud onto a cloth or paper towel. I haven't had anything come out yet.

Sorry, you are confusing the stock air filter box breather system drain with the plenum overflow drain.  These serve two different functions.
The bladder tube you describe would still allow gas to pool in the plenum chamber.  The pinch tube is the correct function for the filter box drain only, not the plenum chamber.
The K&N setup will route all the water condensate and other vapors/gasses to the combustion chamber, to be burned there.

Cheers,

But wouldn't an open tube in the plenum chamber introduce air into an already restricted air infiltration system? My plenum/airbox chamber came from a bike that was all stock but all the rubber was brittle and broken. But the squeeze nipple tube was the one attached to the plenum drain. The open drain tube was attached to the filter box outside of the realm of the filter system. In theory it makes sense to me.

[TwoTired]

But wouldn't an open tube in the plenum chamber introduce air into an already restricted air infiltration system?

Some, yes.  That is why it has restricted diameter and has a some open cell foam stuffed into the end of it. The carb jetting was determined with that air introduction/offset to the induction pressures.  (I rather object to your assumptive stating that the stock induction is restricted".  But, that is another matter, and different discussion.)
The drain is an engineering trade off, or necessary evil.  Pooled gasoline is quite the fire hazard in that location. A small backfire and much of that area will be reduced to a puddle of molten plastic, or possibly tiny bits from an explosion (explosive gasses in a confined space only need an ignition source).  If the engine starts and runs fast enough, it could alternately ingest a large quantity of raw liquid which can hydro-lock a running engine, and bend or snap a rod(s).

http://www.cmsnl.com/honda-cb550k0-four-usa_model465/partslist/F++05.html
It's item 26.  Note no pinch end.  And the #31 tube that is supposed to have the pinch fitting, is not available.

My micro fiche also shows the pinch nipple on the filter box drain, but not on the air chamber box.

My plenum/airbox chamber came from a bike that was all stock but all the rubber was brittle and broken. But the squeeze nipple tube was the one attached to the plenum drain.

I assure you the factory didn't put that squeeze nipple in that position.
I've had these bikes since 1975, and have replaced those hoses many times when they were still available from Honda.  Different part numbers and different assigned locations.

The open drain tube was attached to the filter box outside of the realm of the filter system.

An open drain at that breather location defeats much of the breather design function, as it allows an atmospheric pressure "vent" or source at the wrong place in the apparatus.  The filter chamber negative pressure is to be applied to the crankcase for positive evacuation of blow by gasses, condensate vapors, or other oil hydrocarbons.  Instead, the open end will just suck up dirty air from beneath the vehicle, and which will foul/block the breather filter element (through which the filter chamber vacuum is applied to the engine crankcase).  Crankcase gasses will only vent when the pressure in the crankcase rises and may or may not cycle through the engine's intake system (Not at all, if the element breather filter is blocked).

In theory it makes sense to me.

Honda engineers don't agree with you, I'm afraid.  And, I simply can't support, and must oppose, your theory.  Sorry.  (It' took me a while to fully understand it.)

Cheers,

[xsmooth69x]

But wouldn't an open tube in the plenum chamber introduce air into an already restricted air infiltration system?

Some, yes.  That is why it has restricted diameter and has a some open cell foam stuffed into the end of it. The carb jetting was determined with that air introduction/offset to the induction pressures.  (I rather object to your assumptive stating that the stock induction is restricted".  But, that is another matter, and different discussion.)
The drain is an engineering trade off, or necessary evil.  Pooled gasoline is quite the fire hazard in that location. A small backfire and much of that area will be reduced to a puddle of molten plastic, or possibly tiny bits from an explosion (explosive gasses in a confined space only need an ignition source).  If the engine starts and runs fast enough, it could alternately ingest a large quantity of raw liquid which can hydro-lock a running engine, and bend or snap a rod(s).

http://www.cmsnl.com/honda-cb550k0-four-usa_model465/partslist/F++05.html
It's item 26.  Note no pinch end.  And the #31 tube that is supposed to have the pinch fitting, is not available.

My micro fiche also shows the pinch nipple on the filter box drain, but not on the air chamber box.

My plenum/airbox chamber came from a bike that was all stock but all the rubber was brittle and broken. But the squeeze nipple tube was the one attached to the plenum drain.

I assure you the factory didn't put that squeeze nipple in that position.
I've had these bikes since 1975, and have replaced those hoses many times when they were still available from Honda.  Different part numbers and different assigned locations.

The open drain tube was attached to the filter box outside of the realm of the filter system.

An open drain at that breather location defeats much of the breather design function, as it allows an atmospheric pressure "vent" or source at the wrong place in the apparatus.  The filter chamber negative pressure is to be applied to the crankcase for positive evacuation of blow by gasses, condensate vapors, or other oil hydrocarbons.  Instead, the open end will just suck up dirty air from beneath the vehicle, and which will foul/block the breather filter element (through which the filter chamber vacuum is applied to the engine crankcase).  Crankcase gasses will only vent when the pressure in the crankcase rises and may or may not cycle through the engine's intake system (Not at all, if the element breather filter is blocked).

In theory it makes sense to me.

Honda engineers don't agree with you, I'm afraid.  And, I simply can't support, and must oppose, your theory.  Sorry.  (It' took me a while to fully understand it.)

Cheers,

it makes me wet when you talk nerdy twotired. you mind is a abyss of information on our loved bikes!

[Duanob]

Jeez I feel like just got PWNED in a court of law. I'll change them out....before the Honda po-po show up at my door!

[caluser2000]

#2 is the answer.

The plenum box lower fitting is a drain in the event that carbs overflow and try to pool raw gas in that plenum.  That would be bad.  Potential flambe`.

The original drain tube is a reduced diameter molded type.  The reduced diameter restricts the amount of air that can bypass the air filter.  Also the end of the tube had some open cell foam stuffed in it, to keep critters from venturing into an inviting dark hole for nest building.

Cheers,

Makes sence.