Author Topic: Breather? (Read 20535 times)

TwoTired · « **Reply #25 on:** September 20, 2010, 11:41:17 PM »

Quote from: Don R on September 20, 2010, 10:28:54 PM

I recently put the factory breather back on my 76F and posted the question about hose routing. There are three nipples on the breather, I assume the top one is fed from the crankcase breather where do the other two go? The oil tank does not seem to have any unused outlets and the tank overflow goes to the lower engine fitting.

I looked here:
http://www.cmsnl.com/honda-cb750f-750-super-sport-76-us_model490/partslist/F++15.html
The one at the bottom is a water drain. The end of this hose should be capped with a "pinch" slot in it.

The top nipple should attach to the nipple at the top of the air box.

The middle nipple should attach to the cylinder head cover outlet.

Cheers,

cobra2411 · « **Reply #26 on:** March 23, 2011, 11:39:50 AM »

Ok, I'm going to revive this thread. I have a 76F also and it's missing the breather/separator. It has a 71 engine and probably a 71 filter housing (no fitting at the top). Right now the bike has pods and the crank, valve cover and oil tank breathers are just routed down behind the engine.

I'd like to come up with something a little better then just spewing out blow-by and oil vapors. Any working diagrams on how everything should fit together and substitute parts? I saw a mention of an air tool air/oil separator but the ebay ad is old and the picture doesn't work.

David

cookindaddy · « **Reply #27 on:** March 23, 2011, 02:43:26 PM »

I think it would be tough to do with the pods since you don't have the vacuum source provided by the Honda airbox.

TwoTired · « **Reply #28 on:** March 23, 2011, 02:59:05 PM »

You won't like it, I would guess. But, you could make a log manifold of sorts that fit across the far end of the pods. Drill and insert a T into the end of the them, link them all together and then to the engine breather hose. It might also serve to balance the 4 independent intakes and the same time.

Another approach might be at the vacuum taps where you attach the manometers for balancing the carbs. Not saying this is without issues. Just maybe. Maybe a PCV valve would help out there. Thinking out loud.

Cheers,

cobra2411 · « **Reply #29 on:** March 23, 2011, 03:20:46 PM »

Oh, I guess it would have been good to say I was going back to the Honda airbox on this bike...

Oops...

If I was going to keep the pods I would have just vented them to one of the inner pods and not worried about how effective it was.

I don't know if I just need to run them to the air filter or do I need to have a breather/separator?

TwoTired · « **Reply #30 on:** March 23, 2011, 03:58:39 PM »

For one thing, you don't want to run all the crankcase vapors through the filter element, as it will just foul it. Gases; yes, water and oil droplets; no. Water Droplets will make paper fibers weak, where suction will then make them collapse on themselves, making the filter membrane more restrictive.

Honda went to a lot of extra expense and development to add that separator to the bikes. Hard to believe it is superfluous. I think without it, you'll be replacing air filters more often, or running it with a partially clogged filter for a longer duration. (Poor average MPG and maybe fouled spark plugs.)

Is there a particular reason why you don't want it?

Cheers,

cookindaddy · « **Reply #31 on:** March 23, 2011, 04:03:48 PM »

The Honda separator works fine here. I had to add it back to my bike since the PO probably thought that it was superfluous.

Nortstudio · « **Reply #32 on:** March 23, 2011, 04:13:38 PM »

Sorry if this is an incredibly stupid question, but is there an element that I don't see on my bike, or in the parts fiche? Can someone tell me the number on a '76 CB550k???

I have the tube that goes from the valve cover, and attaches to the bottom of the stock air filter holder/case. I do have the metal "grate" at the bottom of the case, is this what you're talking about?

Just trying to figure out if this is another part that was missing from the POs wonderful care of this beast. Thanks for the clarification.

TwoTired · « **Reply #33 on:** March 23, 2011, 04:36:17 PM »

The Cb550s have a breather and droplet separator at the bottom of the air filter box.

The bottom is the drain that is usually plugged. (drained at service intervals).
The top cover engine breather hose attaches to the side of the air filter box.

In the bottom of the filter are two metal components. One is a plate with perforated holes. On top of that is Foam element holder and the bottom edge has a rubber seal. The holder has a tube the extends up into the middle of the air filter element.
Check out chapter 8 Of the Honda Shop Manual to see it's depiction. And chapter 16 figs. 2-12, 2-13, and 2-14 for more pictures.

HOWEVER, for some inexplicable reason, the 76 cb550K model only didn't use this out of all the Cb550s. See Chapter 17 (HSM). I don't know how they got this past the EPA at the time.
I know the breather/separator was back in use on the 77 and 78 models. I don't think I'd want to run without it, personally.

Cheers,

cobra2411 · « **Reply #34 on:** March 23, 2011, 05:13:03 PM »

Quote from: cookindaddy on March 23, 2011, 04:03:48 PM

The Honda separator works fine here. I had to add it back to my bike since the PO probably thought that it was superfluous.

It would be nice if I actually had one... What can I use in it's place?

Nortstudio · « **Reply #35 on:** March 23, 2011, 05:13:17 PM »

Thanks TT. I have the shop manual, and I will check that. I was looking through the parts list and not seeing anything titled with the same terminology used in this thread.

Are you suggesting I get one of these somewhere? Would it fit right into my '76, despite not being stock?

If I may say, this may be the first time I've seen you go "anti-stock"

TwoTired · « **Reply #36 on:** March 23, 2011, 05:30:56 PM »

Quote from: Nortstudio on March 23, 2011, 05:13:17 PM

Thanks TT. I have the shop manual, and I will check that. I was looking through the parts list and not seeing anything titled with the same terminology used in this thread.

http://www.cmsnl.com/honda-cb550k2-four-usa_model464/partslist/F++05.html
Check out 27, 28, 29, 30.

Quote from: Nortstudio on March 23, 2011, 05:13:17 PM

Are you suggesting I get one of these somewhere? Would it fit right into my '76, despite not being stock?

I never had a 76K. So, I don't know if your filter box has the side and bottom hose fittings. They should be blocked off it not connected. But if not, you would have to locate a filter box, too. FYI, my 76 F has the breather recirculator.

The device helps keep the condensation from collecting in the crankcase due to the negative pressure it provides. I would fit it back on the bike if it didn't have one.

Cheers,

Nortstudio · « **Reply #37 on:** March 23, 2011, 05:57:03 PM »

Yep, saw those parts on the list, figured that had to be them - just wanted to clarify.

My air box has the side hose fitting (that connects by hose to the valve cover) and one at the bottom. But the bottom never had a hose - so I bought a replacement from the auto store and ran it down towards the ground - similar to the way it shown in the fiche (part 31 and the unnumbered piece below it).

At the bottom of the air filter case itself, I currently have only the metal part with the holes in it (possibly 30 on the parts list - hard to tell). I have cleaned it, but there are no other Parts in the bottom of the air cleaner case.

Sorry to be a pain, but can you tell me exactly which part is the recirculator? Or is it really the combination of 27-30?

TwoTired · « **Reply #38 on:** March 23, 2011, 06:25:42 PM »

Quote from: Nortstudio on March 23, 2011, 05:57:03 PM

Sorry to be a pain, but can you tell me exactly which part is the recirculator? Or is it really the combination of 27-30?

Ouch Ouch Oow Oww.

The recirculator is pretty much all of them working together. The drain tube needs to be plugged so air doesn't bypass the filter.
The foam part helps keep what the engine gets, particle free.
The stand pipe thing gets the engine gasses past the air filter element, so it won't foul.
The bottom of your air filter element should have a hole in it. If the stand pipe thing isn't there, the air box air can just bypassed the filter membrane through that hole.

The whole thing operates via the vacuum inside the air filter at the top of the stand pipe.

Cheers,

Nortstudio · « **Reply #39 on:** March 23, 2011, 06:57:40 PM »

So given my current set-up (one hose from valve cover, one going straight down to the ground), should I plug the drain hole/tube? Is that causing it not to work as prescribed by Honda?

Or could I put some type of foam inside the metal housing at the bottom to approximate the flow that should be happening?

I'd like to have this thing running as best it can (for the bike AND for the environment) if possible, just so I can eliminate it's I'll effects from the list of things that may be effecting the performance of the bike.

I forgot to mention that my UNI filter has the small circular foam at the bottom, that faces down at the area we are talking about.

I guess I can start looking around for the elements to replace the whole thing too.

Really appreciate the time you have spent on this. Who knew that there was yet another thing on this bike that would come back to bike me in ass???

Nortstudio · « **Reply #40 on:** March 23, 2011, 07:12:57 PM »

I found this on eBay. It definitely has more parts than mine does.

http://cgi.ebay.com/ebaymotors/1976-76-Honda-CB550-CB-550-Airbox-Air-Box-_W0QQcmdZViewItemQQhashZitem19c309a94cQQitemZ110646372684QQptZMotorcyclesQ5fPartsQ5fAccessories#ht_1254wt_722

Might this work?

TwoTired · « **Reply #41 on:** March 23, 2011, 07:30:45 PM »

Looks like the ebay deal is only missing that thin piece of open cell foam. Should work.

I'm not sure how you can make what you have now work right without all the parts.

Quote

So given my current set-up (one hose from valve cover, one going straight down to the ground), should I plug the drain hole/tube? Is that causing it not to work as prescribed by Honda?

If you plug the drain hole screw now, all the droplets as well as gas vapors will have to go through the Uni filter membrane. That could actually work ok, except you have to clean it more often. But, then you can clean the foam. A paper filter would just foul, collapse and clog.

Is the top of your filter box open? or do you have the tool tray, rubber fitting piece, and screen opening for air inlet. Those parts help maintain the proper air box pressures for the breather, as well as the carbs, to work as originally designed.

Cheers,

Nortstudio · « **Reply #42 on:** March 23, 2011, 07:47:21 PM »

I have the tool tray (just got it!) and it has the screen in the tray. I don't think I have any rubber fitting piece. I will check in the morning, if I'm not covered in snow again!!!!

I also have the small hole/foam part of the uni filter aimed to the bottom facing the drain hole.

I checked bikebandit for the parts, but they don't carry them. I'll keep looking. In the meantime, I can just clean the filter more often. How often do you usually clean your UNI filter (i thought I remembered that you use them as well)?

TwoTired · « **Reply #43 on:** March 23, 2011, 11:06:59 PM »

Quote from: Nortstudio on March 23, 2011, 07:47:21 PM

I checked bikebandit for the parts, but they don't carry them. I'll keep looking. In the meantime, I can just clean the filter more often. How often do you usually clean your UNI filter (i thought I remembered that you use them as well)?

About every six months-ish. But, I don't have missing pieces in the air box.

Cheers,

Nortstudio · « **Reply #44 on:** March 24, 2011, 11:32:38 AM »

Thanks TT. With the missing parts, maybe I should be on a tighter schedule - like every few months. At least until I find the parts.

TwoTired · « **Reply #45 on:** March 24, 2011, 01:04:20 PM »

I use the trip meter to measure distance between fill-ups. As the filter get restrictive, it uses gas faster. That can also tell me when tune-ups are needed, as well.

Nortstudio · « **Reply #46 on:** March 24, 2011, 02:15:17 PM »

I've been doing my best to get her up to snuff, but got bogged down in the 'wrenching on the curb during blizzards sorta sucks' vibe we had going on this year, here in NYC

. So I'm back to it.

But if MPG is any indication, I'd need a tune-up every 15 miles! I haven't kept a super close eye on MPG, but I'd say I'm in the 25/gallon range. Not sure how that stands for city stop and go.

I'm getting there....slowly. Very slowly.

cookindaddy · « **Reply #47 on:** March 24, 2011, 02:33:50 PM »

Nort, if my experience is any indication, you should be able to do significantly better, at least with highway mileage. I carefully checked on two long runs last summer 45-50 mpg. You'll get there but maybe not in the city.

Nortstudio · « **Reply #48 on:** March 24, 2011, 02:47:24 PM »

Photos for "clarification"

Not sure that these will help much - but after looking at my air filter case - I see that in the bottom, with the little bronze colored perforated metal filter removed, there is only the (drain?) hole that goes straight down, and the one that goes out to the right side that is connected to the breather hose.

The bronze filter type deal is hollow inside, doesn't have any foam or anything, and has no way to open it. Didn't want to force it.

I now need to know what I should be doing with this drain hole/hose, while I have the current set-up?

Thanks guys.

TwoTired · « **Reply #49 on:** March 24, 2011, 03:17:37 PM »

Given you have the UNI foam air filter, I recommend connecting the side fitting to the engine cover.

The bottom fitting is fitted with a "pinch tube". The original was a reduced diameter hose and was capped at the bottom. The Cap had a slit cut into it where it it could block air flow, but still allow fluids to leak out (such as if the filter box filled with gasoline). Water and sludge may accumulate down there. So, at service intervals, the tube was pinched to allow anything collected to drain out.

Connecting this way will allow engine crankcase gasses to flow into the carbs via the air filter. Later when you collect the missing parts, those vapors will bypass the filter element and go directly to the carb inlets.

Quote from: Nortstudio on March 24, 2011, 02:15:17 PM

But if MPG is any indication, I'd need a tune-up every 15 miles! I haven't kept a super close eye on MPG, but I'd say I'm in the 25/gallon range.

It is not absolute MPG that determines my filter and tune up attention. It is trend info. If you drive a set route, you know what the bike gets in good tune, clear air filter. When I had to switch to reserve I note the miles driven. The Fs and Ks have different tank size, so it is not the same miles driven for both. Anyway, you learn what is normal for the bike. And then note each time you switch to reserve. If I noticed I got, say 25-50 less miles than normal, Then that would send me looking for the reason. I'd clean the filter check the tuneup stuff, change oil if it looked and felt bad, etc. After doing that, invariably the miles before needing reserve would go back to "normal" for that bike.

Having said all that, I must say that 25 MPG for a 550 is major suck. Gearing, tune, or outright faults are indicated. I suppose if you did all your driving in first gear, ok maybe. Otherwise, you got some tweaking to do, imo,

Cheers,

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Author Topic: Breather? (Read 20535 times)