Author Topic: CB550 breather tubes, what goes with what?  (Read 16112 times)

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Offline mazingerzeca

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CB550 breather tubes, what goes with what?
« on: March 13, 2012, 03:31:23 am »
Hello all.
I'm almost finishing my cb550 rebuilt, but I have lot of doubts about which tube shoul be connected to what. There is a pipe on the bottom of the air filter distributor box (#12 in picture 1), which has a tube (#17) which should be connected somewhere. Also, in this picture, there are another two pipes in the air filter box (#13) which are connected somewhere else. I suspect that #23 is connected to #17, and #22 is either connected to cylinder head breather (#26 in picture 2) or left to drain to the air, in which case the #26 on picture 2 should be left to open air too? If anyone knows anything about this conundrum or has any picture, it should be useful. Thank you.

Offline SohRon

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Re: CB550 breather tubes, what goes with what?
« Reply #1 on: March 13, 2012, 05:39:53 am »
17 and 22 are the drains for the plenum and air box respectively and route down between the frame and swingarm. 23 is a connector for the blow-by from the engine, and connects to it via a hose (26) between this fitting and the breather cover (3).
« Last Edit: March 13, 2012, 05:43:42 am by SohRon »
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Assembling my '74 CB550: http://forums.sohc4.net/index.php?topic=86697.0
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Offline Duanob

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Re: CB550 breather tubes, what goes with what?
« Reply #2 on: March 13, 2012, 08:12:18 am »
#17 is connected to the bottom of the plenum chamber #12. It's just a condensation drain.
"Just because you flush a boatload of money down the toilet, doesn't make the toilet worth more",  My Stepfather the Unknown Poet

1974 CB360T
1976 CB550K2 Resurrected
1976 CB550F2 Barn Find
1979 CX500 VG "HONDA-GUZZI"
2007 Moto Guzzi Breva 750ie
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Offline mazingerzeca

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Re: CB550 breather tubes, what goes with what?
« Reply #3 on: March 16, 2012, 01:36:42 am »
Thank you for your help. I'll do that.

Offline TwoTired

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Re: CB550 breather tubes, what goes with what?
« Reply #4 on: March 16, 2012, 02:29:06 am »
#17 connects to #12.  It is not an ordinary tube.  It is a reduced diameter hose and the end is stuffed loosely with open cell foam so as not to suck in bugs and big volumes of air.

#22 connects to the bottom of #13. This tube has a cap on the end with a slit in it, called a "pinch tube", as the slit opens to drain water when pinched.

#23 in the first pic connects to #26 in the second pic. (engine breather hose)

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

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Offline Scott S

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Re: CB550 breather tubes, what goes with what?
« Reply #5 on: May 01, 2012, 01:05:18 pm »
#17 connects to #12.  It is not an ordinary tube.  It is a reduced diameter hose and the end is stuffed loosely with open cell foam so as not to suck in bugs and big volumes of air.

#22 connects to the bottom of #13. This tube has a cap on the end with a slit in it, called a "pinch tube", as the slit opens to drain water when pinched.

#23 in the first pic connects to #26 in the second pic. (engine breather hose)

Cheers,

 Look at me! Look at me! I'm using the search feature!

 Since #22 is NLA, should I just leave it open or maybe find a piece of fuel line or vacuum hose to go on the nipple?

 And how, exactly, is #26 routed? I have it going over the top of the plenum and down between the air filter box/battery box. It seems a little short that way. Should it go down between the carbs or ? ? ?
 Pics are ALWAYS helpful for us idiots. :)
'71 CB500 K0
'17 Triumph Street Scrambler
'81 Yamaha XS650

Offline Duanob

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Re: CB550 breather tubes, what goes with what?
« Reply #6 on: May 01, 2012, 02:49:50 pm »
Hey Scott,
I took a mouth piece tube and nipple from an old camelback drinking tube and some vacuum line to adapt to the drain. Used some zip ties and silicon sealant and it works like a charm.

the main breather tube can be routed down between carb # 3 & 4 and back to the filter box inlet on the bottom side.
"Just because you flush a boatload of money down the toilet, doesn't make the toilet worth more",  My Stepfather the Unknown Poet

1974 CB360T
1976 CB550K2 Resurrected
1976 CB550F2 Barn Find
1979 CX500 VG "HONDA-GUZZI"
2007 Moto Guzzi Breva 750ie
2015 BMW F700GS
Another 1976 CB550K Cafe?

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Offline TwoTired

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Re: CB550 breather tubes, what goes with what?
« Reply #7 on: May 01, 2012, 04:13:41 pm »
Since #22 is NLA, should I just leave it open or maybe find a piece of fuel line or vacuum hose to go on the nipple?
No. An open tube will bypass the breather system and feed dirty air the element filter.  You need to block the end with something, preferably with a device that blocks air ingress, but will allow water to seep/drip out.

And how, exactly, is #26 routed? I have it going over the top of the plenum and down between the air filter box/battery box. It seems a little short that way. Should it go down between the carbs or ? ? ?
It routes down under the carbs (kinda between 3&4) to the filter box.  The Honda shop manual shows the routing of this (550 addenda), if I remember correctly.
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Scott S

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Re: CB550 breather tubes, what goes with what?
« Reply #8 on: May 01, 2012, 07:12:17 pm »
 I was also looking through my pics and I think I see what I did wrong on the airbox. It's a little hard to see here without enlarging the pic, but I should have ran the breather hose down between the manifold on the engine side and then to the air box, just as you guys suggested. I bet if I did that, I could get the hose in place, the breather box to sit right and the snorkle back on.


 I'll have to see what I can come up with on part #22.....any suggestions, other than the camelback mouthpiece, since I don't have one of those!
 Maybe a piece of tube with some sort of filter on the end?
'71 CB500 K0
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'81 Yamaha XS650

Offline TwoTired

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Re: CB550 breather tubes, what goes with what?
« Reply #9 on: May 01, 2012, 09:59:31 pm »
A tube, and cap with a slit from a micro saw across the end.
Nauturaly, closed, pinch to open it's "mouth". 

Hardware store has those vinyl caps, think.  Rubber cement to glue it on the end. 

Just spit balling some ideas.
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

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Offline SohRon

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Re: CB550 breather tubes, what goes with what?
« Reply #10 on: May 02, 2012, 12:15:51 am »
That hose attaches at the breather cover...




...then routes down past the  carbs...




...and attaches at the base of the filter box




The drain is a special hose that fits on the bottom of the filter box




It and the drain for the plenum are basically the same, but with significant differences, as TT pointed out (and he is what learned me all of this stuff). The plenum hose (BikeBandit has it) is about 4-5 inches longer and has a foam filter inside the exposed end, while the filter box drain hose is shorter and has a special tip that looks and works like this:




It drains condensed oil and water from the filter box. It needs to be kept closed, as TT said, to avoid pulling road debris and crud into the filtration system, among other things; but it must be able to act as a valve when necessary.

The above depicted little plug has to be one of the rarest items available on the planet as I have searched high and low and have yet to come across one... in fact, the short hose is now obsolete, as well, so that neither it or the special plug are available.

Fortunately, you can still get the long hose for the plenum, so what I did was buy two hoses ($7.50 ea, IIRC) and cut one down to size for the filter box. I found a little rubber plug that fits tight but can be removed when I'm doing maintenance



It should work 'til, if and when I get the correct tip.


Hope all this helps.



« Last Edit: May 02, 2012, 12:27:50 am by SohRon »
"He slipped back down the alley with some roly-poly little bat-faced girl..."

Assembling my '74 CB550: http://forums.sohc4.net/index.php?topic=86697.0
Assembly of the Right-hand Switch (a rebuilder's guide):  http://forums.sohc4.net/index.php?topic=80532.0
Installing stock 4X4 exhaust: CB500-CB550 K: http://forums.sohc4.net/index.php?topic=82323.0
CB550 Assembly Manual: http://forums.sohc4.net/index.php/topic,151576.0.html

Offline LesterPiglet

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Re: CB550 breather tubes, what goes with what?
« Reply #11 on: May 02, 2012, 01:42:52 am »
Would an inline fuel filter work for this?
'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


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Offline Scott S

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Re: CB550 breather tubes, what goes with what?
« Reply #12 on: May 02, 2012, 03:53:59 am »
 SohRon, now that's what I'm talking about! Excellent pics.

 I'm lucky enough to have the plenum hose and all the other pieces.

 Lester....good idea. I fuel filter would still act as a filter on the inlet side but let fluids flow past.
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Offline Duanob

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Re: CB550 breather tubes, what goes with what?
« Reply #13 on: May 02, 2012, 09:30:25 am »
.....any suggestions, other than the camelback mouthpiece, since I don't have one of those!
 Maybe a piece of tube with some sort of filter on the end?

You can buy just the camelback pinch tip at a sporting goods store for about $6 then use sealant and rubber vacuum line for the rest. You just need to be able to drain it every now and then.
"Just because you flush a boatload of money down the toilet, doesn't make the toilet worth more",  My Stepfather the Unknown Poet

1974 CB360T
1976 CB550K2 Resurrected
1976 CB550F2 Barn Find
1979 CX500 VG "HONDA-GUZZI"
2007 Moto Guzzi Breva 750ie
2015 BMW F700GS
Another 1976 CB550K Cafe?

  __o
_- \_<,
(*) /' (*)

Offline TwoTired

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Re: CB550 breather tubes, what goes with what?
« Reply #14 on: May 02, 2012, 12:39:33 pm »
Would an inline fuel filter work for this?

I won't recommend this.  The breather system needs to evacuate the engine crankcase.  An open bottom hose will bypass/equalize any suction sourced in the air filter box that was intended for the crankcase.  Think of a "Y" shaped drinking straw, with only one end in the fountain drink.  Unless you suck REALLY hard, you'll stay thirsty.  :D

However, after the fuel filter element became blocked with water/oil emulsion, then it would be of proper service.  (This just seems perverted to me, though.)   ;D    The filter has to clog to work in the system properly??  (Scratches head.)  ???

You know that extra green wire near the turn flasher?  Maybe we could find a good use for an inline fuel filter installed onto that?  That should raise the eyebrows of a service mechanic a few years down the road.  ;D ;D  /jk

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline PrsCustom22j

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Re: CB550 breather tubes, what goes with what?
« Reply #15 on: May 02, 2012, 12:44:38 pm »
great post...i'm trying to get mine back on CB550K too.     ;D
1976 Honda CB550K

Offline Tews19

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Re: CB550 breather tubes, what goes with what?
« Reply #16 on: May 04, 2012, 09:13:49 pm »
That hose attaches at the breather cover...




...then routes down past the  carbs...




...and attaches at the base of the filter box




The drain is a special hose that fits on the bottom of the filter box




It and the drain for the plenum are basically the same, but with significant differences, as TT pointed out (and he is what learned me all of this stuff). The plenum hose (BikeBandit has it) is about 4-5 inches longer and has a foam filter inside the exposed end, while the filter box drain hose is shorter and has a special tip that looks and works like this:




It drains condensed oil and water from the filter box. It needs to be kept closed, as TT said, to avoid pulling road debris and crud into the filtration system, among other things; but it must be able to act as a valve when necessary.

The above depicted little plug has to be one of the rarest items available on the planet as I have searched high and low and have yet to come across one... in fact, the short hose is now obsolete, as well, so that neither it or the special plug are available.

Fortunately, you can still get the long hose for the plenum, so what I did was buy two hoses ($7.50 ea, IIRC) and cut one down to size for the filter box. I found a little rubber plug that fits tight but can be removed when I'm doing maintenance



It should work 'til, if and when I get the correct tip.


Hope all this helps.

I did this to my 550F today.. The exhaust breather was not on the airbox... When it was disconnected I could see air/white smoke like when the air from an exhaust is colder then the air around.....

Now today I tried to start my bike and it had a hard time... After i got her running she wouldnt stay idling... I turned her off and saw a huge puddle underneath the bike. It wasnt there prior to hooking up my exhaust breather to the airbox... What gives?
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline TwoTired

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Re: CB550 breather tubes, what goes with what?
« Reply #17 on: May 04, 2012, 11:50:14 pm »
Do you have the internal breather element components for the bottom of air filter and the stand pipe to feed the vapors into the air plenum bypassing the air filter? (Parts 27, 28, 29, and 30)

Is the breather element soaked with water/oil emulsion?
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Tews19

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CB550 breather tubes, what goes with what?
« Reply #18 on: May 07, 2012, 07:11:38 am »
I have everything minus the foam part. Any type of foam work? How thick should I be? Thanks TT for the heads up. Once I get the foam this will help with the condensation from seeping out?
1969 Honda CB750... Basket case
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Offline TwoTired

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Re: CB550 breather tubes, what goes with what?
« Reply #19 on: May 07, 2012, 12:28:44 pm »
I have everything minus the foam part. Any type of foam work? How thick should I be? Thanks TT for the heads up. Once I get the foam this will help with the condensation from seeping out?
I've never run the bike without the foam element.  So, it's hard to identify with the "problem" you present.
I was told the foam element is NLA from Honda.  It needs to be open cell foam, about 1/4 inch thick, and gas/oil resistant to break down.  The foam cells should be rather fine, equivalent in filtering tunnel size as the main air filter element.
The function of this part is to keep unfiltered air from bypassing the main air filter, which would happen if the engine breather filter hose or the bottom drain hose failed or fell off.  This would otherwise induce more rapid engine wear simply from a hose failure that could go unnoticed for thousands of miles.  It also collects condensation, until the gasses from the crankcase get hot enough and have enough volume to re-vaporize it, there and carry it into the engine to be burned.

The main purpose of the engine breather is to evacuate the engine crankcase.  The filter box drain does drip occasionally from the collected water, even with the proper end plug.   The amount of dripping will be related to the humidity and just how much water is collected in the engine crankcase.
If drips are an issue for you, I'd guess you haven't run the bike very long with the breather fully operational.  Or, you are doing a lot of short trips where the crankcase can't achieve full operating temp long enough to fully vaporize the collected condensation.

I know in the winter months here when humidity is high and I ride in occasional rain, I have to clean that breather element about once a month to keep it clear and flowing.  The foam does retain some water during these periods, and can clog completely, which promotes rust on those element retainer parts.  It is not a maintenance free system.  But usually, its attention usually coincides with the 3000 mile maintenance interval.

I will mention that some have substituted a scotch bite pad for the element foam.  But, I don't think it can hold the water collected over 3000 miles. (depends on your climate).

Anyway, the proper foam provides a collection point for the condensate, under normal circumstances.  If the drain hose starts dripping at the slitted cap, then it probably needs cleaning/clearing.

For all the lengthy explanation above, it simply works quite well under most circumstances, with minimum attention.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline vsanzbajo

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Re: CB550 breather tubes, what goes with what?
« Reply #20 on: June 26, 2018, 11:24:10 am »
I am confused about a third nipple in the air cleaner chamber, not the box. What is connected there. Right now I just plugged because I have no clue where it goes to. I am clear about the crankcase tube to the right side of airbox, and the pinch tube under the airbox, but that this one from the air cleaner chamber I have no idea. Anyone?

Offline TwoTired

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Re: CB550 breather tubes, what goes with what?
« Reply #21 on: June 26, 2018, 12:23:21 pm »
The air plenum nipple is a drain, so if/when the carbs overflow, the plenum doesn't pool gasoline.  It was a molded hose from Honda that reduced the diameter down to about 1/8 inch and had a little bit of open cell foam stuffed in the end.  The small diameter end let in very little air, while keeping the bugs and sand out.  Yet, it would drain any gas overflow out of the plenum without allowing it to pool, catch fire, or compression lock the engine.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline vsanzbajo

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Re: CB550 breather tubes, what goes with what?
« Reply #22 on: June 26, 2018, 12:40:38 pm »
So Right now I have a plug, so would you just cut the tip off?
« Last Edit: June 26, 2018, 12:48:47 pm by vsanzbajo »

Offline TwoTired

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Re: CB550 breather tubes, what goes with what?
« Reply #23 on: June 26, 2018, 12:46:01 pm »
You'll have to better define "plu".

But, the stock hose routed down between swing arm and engine case, so it would dump pooling gas on the ground instead of all over the back of the engine.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline vsanzbajo

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Re: CB550 breather tubes, what goes with what?
« Reply #24 on: June 26, 2018, 12:49:04 pm »
Plug, sorry