[1967 Honda CD125]

I am almost finished restoring my 1967 Honda CD125, and have a question about a "vacuum" port on the top of the valve cover. When I got the bike, there was no hose attached to it, and it acutally had a small mud-dobber's nest packed in the hole. I am guessing that there should be a hose coming off, but where does it go? Is it supposed to go down and disappear behind the engine?

Is this designed to release air/pressure as the oil pump pumps oil up into the sealed valve rocker assembly area?

If the line gets clogged (for ex., from an onwry mud-dobber), is there another way for the engine to release the pressure, or will oil oooz out someplace?

Thanks.

Pic of the vacuum port:
If you look at the top of the engine, you will see the small hole where I assume a hose should be attached:

 

[mike in idaho]

It's a breather hose fitting it's there to let crankcase pressure and fumes out. If it's plugged, pressure will build up, cause oil leaks and blow out seals.

 

[1967 Honda CD125]

It's a breather hose fitting it's there to let crankcase pressure and fumes out. If it's plugged, pressure will build up, cause oil leaks and blow out seals.

Thanks for the reply Mike.......Ok, a breather hose is supposed to be attached, but where is it supposed to go? Do you just cut a 1 foot piece and let it just hang down or what? Im thinking that it would be good to make a small screen to go on the end to keep the varmits out.

 

[zgoldwingman]

Run the hose with and down the main frame with some ties, and let it extend to about the same level as the bottom of the engine.