Topic: I think I’m missing a hose...

[BlackDog66]

Hi, new CB500K1 owner. I got this bike in a few pieces and I’m not sure if I’m missing another part. There is what appears to be a nipple on the back side of the breather cover. I’ve seen some YouTube videos on other parts of the bike and the bikes in those videos  all have a hose attached to this nipple. The manual I have discusses the breather cover removal during the top end overhaul but doesn’t mention a hose to remove, just 6 bolts.

So what am I missing (both literally and metaphorically)?

[Alan F.]

Yup, vent hose.

[BlackDog66]

Awesome, thanks Alan. Not sure how I missed that. So this hose just hangs with no other connection?

As someone who doesn’t know much about how these bikes actually function, what is the purpose of the breather? Why does it need a vent?

[bryanj]

Ll engines need to vent pressure and in the 70's this did not need to be recirced like now so all it needed was a hose to takeany vapour to an out of the way place

[fogrider]

On my 550f that hose goes down behind the carbs and connects to a hose spigot  underneath  the air filter chamber.

Must be worth a look to see if there is such a spigot on yours. It's a git to connect so maybe someone left it off ?

Regards, Terry.

[RAFster122s]

It is part of the breather recirculation system taking air from the top end that may have oil suspended in the air and collecting that vapor and in the bottom of the air filter box is a multi-part filter that separates the water and oil in that vapor. It is often referred to as a positive crankcase ventilation system...early version of one. The air is then filtered before being combined with the fresh air and burned with the gas in the combustion chambers. 

So, yes...a hose leads from the cover to the airbox as was described by fogrider.

Early car motors and bikes just vented to atmosphere.

[Deltarider]

So, yes...a hose leads from the cover to the airbox as was described by fogrider.

So, no, the CB500 did not have that, just a hose that vents in the open.

Early car motors and bikes just vented to atmosphere.

Yep and the CB500 was one of them.

[RAFster122s]

So, yes...a hose leads from the cover to the airbox as was described by fogrider.

So, no, the CB500 did not have that, just a hose that vents in the open.

Early car motors and bikes just vented to atmosphere.

Yep and the CB500 was one of them.

Sorry, thought we were talking cb550. My 74 550 has the hpse to airbox... I failed to notice we were discussing a cb500.

[Deltarider]

So, yes...a hose leads from the cover to the airbox as was described by fogrider.

So, no, the CB500 did not have that, just a hose that vents in the open.

Early car motors and bikes just vented to atmosphere.

Yep and the CB500 was one of them.

Except the much later CB500K3, but only some 4200 were assembled and they all went to continental Europe.

[Mantree]

Same thing on te 750s I put a pcv filter on it to keep dirt out and called it good