breather hoses

mech o1 · Post by **mech o1** » Fri Oct 16, 2009 12:15 am

i have a cb 77e 305 if the breather hoses r of f will it effect the proformance of this motor 0ne of the nipples r broke off so i just took them off bike still runs with them off really good

e3steve · Post by **e3steve** » Fri Oct 16, 2009 1:30 am

If you're referring to the two cyl head 'breathers' beneath the carbs, you can unscrew the spigots and plug the holes. Honda dismissed them as unnecessary; they're not even there on the later models.

kirbb9 · Post by **kirbb9** » Sat Oct 17, 2009 8:03 am

And if you don't plug them off you are pulling unfiltered air into the engine.

Brady

mech o1 · Post by **mech o1** » Sat Oct 17, 2009 8:32 am

thanks guys for the in fo on the hoses superhawks forever cb77e

Vince Lupo · Post by **Vince Lupo** » Mon Oct 26, 2009 5:55 pm

kirbb9 wrote:And if you don't plug them off you are pulling unfiltered air into the engine.

Brady

Debatable (though only my point of view). I asked Bill Silver about this about two years ago, and he told me that there is no vacuum present in these hoses. They are 'vents' - so therefore (theoretically) shouldn't they function like an EGR valve (the air would be going out, rather than coming in)? Any unburned gases get recirculated back into the air filters?

kirbb9 · Post by **kirbb9** » Mon Oct 26, 2009 8:56 pm

Sounds logical to me, Vince. I can see where that could be possible.
Thanks for more info.

Brady

sotxbill · Post by **sotxbill** » Tue Oct 27, 2009 9:31 am

as the pistons go up, the can create a partial vacum, then when coming down, they can pressurize the case. If both pistons are 180 degrees out of phase, then one is going up while one is going down so its about equal. but then there's blowby of compression through the piston rings and thats not equal as one is compressing and that one will blow more than the other.. so there can be periods of slight vacum and lots of periods of slightly to lots more pressure. So that they should blow more than suck... Then you get into which type of oil and will does what is its vaporization ratings. Low grade oils like 30wt non detergents will vaporize and be carried out of the crank case as a fine oil mist. You can expect to loose about 7 to 13% of your oil through the vent. The better grade oils are tested for this exact problem and stay put and do not vaporize and become mist. Part of the api testing as to how much this happens. So pulling off the hoses means you will have oil discharge and goo coming out and have a way for moisture to get into the case when you wash the maching and drive in rain. Cooling cycles will also allow moist air to enter and condense inside the engine. The moisture mixes with combustion compounds and form hydrogen sufide and other acids that reside in the oil and can cause engine wear due to the acid effect. Moisture is a really bad thing to get in the crankcase. HD oils have a base additives and safely handle the problem with moisture and acids. 30wt non detergent oil does not and need to be change more often if you dont control you vent lines. and it will also loose more oil through the case and need to be replinish or changed as well. Lot of superhawks had oil soaked air filters as a result of the breather tubes, cheap oil and blowby from worn rings from the cheap 30wt oil. Oil soaked filters caused the bike to run rich and loose performace due to air starvation as well.

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