Topic: Breather?

[MattFreeman]

If I am calling this canister by it's correct name, breather? Do you still somehow use the small canister in front of the rear wheel if you switch to pod filters?

Or do you pitch it or use something else instead?

Or am I stupid and this thing is not related to the filter at all?

[bollingball]

I did away with mine EPA crap run the hose from valve cover straight down in front of rear wheel like your carb and batt. hoses

[Markcb750]

I put on a air box from a 75F so that I could add this breather and feed to the air box which eliminates dripping oil and smoke puffs from the tube in front of my rear wheel.


Plus it does just a little bit to reduce air pollution at no loss of performance.

[TwoTired]

All the SOHC4s have nuances unique to the their model/type.  Pity you didn't tell us which one you have.

If you are throwing away superior technology in favor of cheap pod filters, you have little choice but to further diminish your machine by dumping carcinogens from the engine breather tube into open air for all the rest of us to breathe and foul our lungs.

In this case, the EPA was trying to save us from spewing crap.  But, many do this in spite of themselves.
In fact, engine breather vapor recirculation improves engine power and efficiency.  Many racing vehicles benefit from this practice.

Cheers,

[bollingball]

I don't have any blowby on mine if you do then use the breather separator just remember to dump it. you don't have to dump it into your air filter. If it is dripping that much oil it may be time to fix the problem rather than oiling up your filter unless it is a K&N then it would be a good thing

[bollingball]

I am rethinking my position on this on my bike 750K8. after looking at the emission control diagram in the service manual the hose coming from the breather separator goes in the top of the airbox an does not go through the filter. I may redo mine.

[TwoTired]

I am rethinking my position on this on my bike 750K8. after looking at the emission control diagram in the service manual the hose coming from the breather separator goes in the top of the airbox an does not go through the filter. I may redo mine.

I applaud your efforts, sir.
Hopefully, what I typed below, (before reading your latest response, above) will help to enlighten other readers.

Cheers,

I don't have any blowby on mine ....

Yes it does.  Piston rings don't make a perfect seal.  All IC engines have blowby whether visible or not.  The amount varies with RPM and wear of the mated parts.

Further, separate from the blowby, the heated oil and water condensate "boil off" each time the engine heats up, an open tube dumps these carcinogens out the breather tube.

Put some oil in a pan and heat it to 200F in your kitchen.  I hear some like the smell and taste of breathing carcinogens.

you don't have to dump it into your air filter.

True, you want it to get burned in the engine's combustion chamber, which is why the stock engine breather recirculation systems bypass the air filter element.

If it is dripping that much oil it may be time to fix the problem rather than oiling up your filter unless it is a K&N then it would be a good thing

What many perceive as oil drips, is actually water with a bit of oil in an emulsion.  The drips occur due to a water condensation and evaporation cycle.  Certainly any IC engine with the crankcase exposed to atmospheric pressure and its content will experience this drip phenomena.  It gets more prominent with high humidities and short or incomplete warm up cycles of the engine oil and crankcase.

There is no rational justification to dumping crankcase vapors into the atmosphere beyond ignorance or maliciousness.  Both reasons are injurious to mammals.

[bollingball]

TT if I run my hose from the valve cover to the top of air box would this work? I don't have the separator.

[drillzzz]

Perfect timing for this thread as I just placed the air box on my 78 cb750k. I was wondering is there a way to purchase the hoses that run to the separator or do I have to buy hoses from an auto store? What sizes are the two hoses running to the separator? Trying to finish my project and then will conclude my thread. Thanks.

[Cqyqte]

I rerouted my cylinderhead breather through an in-line oil/water separator from a compressor supply store and punched two small holes in the the pod filters and JB welded a hose barb into each hole.  I then ran a hose from the output of the separator to a Y and then to the new ports on the pods.

If you don't use the original separator tank or a new style, you'll get water condesate mixing in the carbs with the fuel vapour causing all sorts of corrosion to Cad coated components.  And in short order you'll find your freely moving carbs will start gumming up.

Here's something like what I used. http://cgi.ebay.com/ebaymotors/1-4-NPT-Water-Oil-Separator-Air-Compressor-Tools-_W0QQcmdZViewItemQQhashZitem2c577248a6QQitemZ190445668518QQptZMotorsQ5fAutomotiveQ5fTools  
It works perfectly and has a one way valve to drain the crud off with when full.

[bollingball]

Drill if you are staying with the stock look take the separator to the auto parts store it was thin wall hose measure from valve cover to where you mount the separator then from separator to airbox then add two feet for kicks if you measured correctly then use the extra for the drain on separator make sure the hose is snug on the barbs.

[mystic_1]

There is no rational justification to dumping crankcase vapors into the atmosphere beyond ignorance or maliciousness.

I guess the engineers at Honda were either ignorant or malicious, then, as some models vented their breather tubes straight to atmosphere.

In fact, engine breather vapor recirculation improves engine power and efficiency.  Many racing vehicles benefit from this practice.

Can you expand on this?  I'm aware of the emission benefits but never heard that EGR improves performance.

mystic_1

[Doctor_D]

Can you expand on this?  I'm aware of the emission benefits but never heard that EGR improves performance.

In side by side dyno runs on my Commando, swapping the stock vent line for a reed valve breather (an XS650 unit to be exact) -- T'd into to the balance tube between the carbs -- added a small but measurable amount of power.  This is likely due to the fact that the crankcase was running a slight vacuum. As a bonus, a few minor but persistent oil leaks stopped weeping.

[MattFreeman]

All the SOHC4s have nuances unique to the their model/type.  Pity you didn't tell us which one you have.

Sorry, I do that all the time.

"76 CB 750 F1

[MattFreeman]

I rerouted my cylinderhead breather through an in-line oil/water separator from a compressor supply store and punched two small holes in the the pod filters and JB welded a hose barb into each hole.  I then ran a hose from the output of the separator to a Y and then to the new ports on the pods.

If you don't use the original separator tank or a new style, you'll get water condesate mixing in the carbs with the fuel vapour causing all sorts of corrosion to Cad coated components.  And in short order you'll find your freely moving carbs will start gumming up.

Here's something like what I used. http://cgi.ebay.com/ebaymotors/1-4-NPT-Water-Oil-Separator-Air-Compressor-Tools-_W0QQcmdZViewItemQQhashZitem2c577248a6QQitemZ190445668518QQptZMotorsQ5fAutomotiveQ5fTools  
It works perfectly and has a one way valve to drain the crud off with when full.

Moy excellente!

[TwoTired]

TT if I run my hose from the valve cover to the top of air box would this work? I don't have the separator.

It will cure the vented vapor issues.  But, the water separator is quite desirable to help keep it from settling on carb components.

Cheers,

[TwoTired]

There is no rational justification to dumping crankcase vapors into the atmosphere beyond ignorance or maliciousness.

I guess the engineers at Honda were either ignorant or malicious, then, as some models vented their breather tubes straight to atmosphere.

Yes.  As the models were developed, the breather recirculation and water vapor separator were added in a chronological fashion.  For the cb550 it began in 74.

In fact, engine breather vapor recirculation improves engine power and efficiency.  Many racing vehicles benefit from this practice.

Can you expand on this?  I'm aware of the emission benefits but never heard that EGR improves performance.

EGR (Exhaust Gas Recirculation) is not the same as crankcase gas recirculation.

Negative pressure in the crankcase helps seal piston rings, improves "boil off" of crankcase water vapor, and helps retard the blowby unburned carbons from soaking into the oil supply (by evacuation of those carbons).   Both the reduced water content in the oil and reduced carbon contamination in the oil aid in the longevity of components, reducing wear, which helps keep the engine performing more efficiently over a greater period of time and use.

[MattFreeman]

So is http://www.cb750cafe.com/parts.php?id=87 an acceptable substitute for the factory breather?

[mystic_1]

In fact, engine breather vapor recirculation improves engine power and efficiency.  Many racing vehicles benefit from this practice.

Can you expand on this?  I'm aware of the emission benefits but never heard that EGR improves performance.

EGR (Exhaust Gas Recirculation) is not the same as crankcase gas recirculation.

Negative pressure in the crankcase helps seal piston rings, improves "boil off" of crankcase water vapor, and helps retard the blowby unburned carbons from soaking into the oil supply (by evacuation of those carbons).   Both the reduced water content in the oil and reduced carbon contamination in the oil aid in the longevity of components, reducing wear, which helps keep the engine performing more efficiently over a greater period of time and use.

You're right of course, my bad, misuse of term out of force of habit.

So, sounds like the main performance (power) benefit is from improved piston ring sealing.  Can you compare and contrast this with the PCV found on most modern cars?

mystic_1

[mystic_1]

So is http://www.cb750cafe.com/parts.php?id=87 an acceptable substitute for the factory breather?

Well, that items is more just a filter to keep you from (possibly) sucking up debris into the breather tube.  It doesn't recirculate the gases nor does it affect crankcase pressure.  IMHO it doesn't really accomplish much, if anything you have slight positive pressure in the crankcases from blow-by gasses, so no risk of sucking up anything.  OTOH whatever IS being expelled from the breather tube will soak into the filter paper and eventually drip.

mystic_1

[Deltarider]

Personally I am very happy my bike (model 1976) came without the breather, a device originally found on big trucks, caterpillars and the like. California, always in the frontline to fight symptoms, was eager to pester motorcycle manufacturers with it. On various 550 models I've seen airfilters elements getting wet and fouled, reason why dealers and owners just cut the tube and had it rerouted as shown on p.170 of the Honda Shop Manual (Supplement to CB550K2 ('76). Now they could continue to use Honda genuine airfilter elements and protesting mammals were advised to move to green California. TT will argue that all these dealers and owners didn't know how to look after breather elements, but I maintain that, if you don't check them regularly, very regularly and cer-tain-ly more regularly than in the maintenance schedule, you can expect trouble. When I look at the design of my breather, I can't see how circulating can ever produce extra power, but I am here to learn.

[TwoTired]

So is http://www.cb750cafe.com/parts.php?id=87 an acceptable substitute for the factory breather?

It is certainly not a functional equivalent to factory, as vapors and gases are still dumped into the atmosphere.
I believe these are used cause it's cheap, pretty, and keeps bugs/dirt from entering the crankcase.  They certainly will need to be examined/tested for free flow periodically, as a clogged one of those would actually be detrimental to the engine.

[TwoTired]

So, sounds like the main performance (power) benefit is from improved piston ring sealing.  Can you compare and contrast this with the PCV found on most modern cars?

I don't know how much "instantaneous" power will be gained from improved piston ring sealing, which is what a race only operator would find of interest.  But, the long term benefits of improved engine life will help give a similarly aged engine more power by comparison.
I do know that racers actually use a vacuum pump to run the crank case at significant negative pressure for the expressed purpose of improved piston ring sealing.

PCV is Positive Crankcase Ventilation.  PCV systems have both an air supply port and an evacuation port for the crankcase.  These systems are more about flow volume rather than significant negative pressure.
The PCV systems I am familiar with, tap the manifold vacuum to provide this air flow.  Which is why they have an associated pressure valve so as not to completely ruin the engine function during periods of low vacuum operation.  These systems are primarily to keep vapors from the atmosphere, and to help keep the oil free of carbon contaminants and water integration, not so much for any power enhancement.  In fact, tapping off the vacuum where these do, likely does denigrate engine power in certain operating regimes.

Cheers,

[bollingball]

Well I found my separator now off to get some hose. TT could you look at my other post about front wheel clamps
                                 

                                      Thanks Ken Bolling

[Don R]

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.