CB77 breather hoses

[prodigal son]

While cleaning my bare cylinder head I found the 2 breather hose ports slightly between and below the intake ports vent to inside the intake valve guides. I have never seen this before. Can someone explain the purpose of how this works? Thanks, Gary

[Tim Allman]

The story I have heard is that they attached to the air filters with the intent of drawing oil into the valve guides. Original air filters have the connectors but newer ones don't so it seems that Honda thought them unnecessary. I have some little rubber caps over mine but there seems to be no harm in leaving them open.

[prodigal son]

Tim thanks for the response. I believe this bike is very original and sat since 1991. The hoses go to a plastic "Y" and are routed through the tin transmission cover along with the breather hose from the head cover. The ends are open to atmosphere there. Not sure how any oil could be drawn in from there. The intake ports are usually in a vacuum state so they would be drawing air into the valve guide? I'm still confused. Thanks again, Gary

[Tim Allman]

Actually, I got it wrong. They were supposed to lower the pressure and reduce the oil getting into the valve guides. There was also something to do with the also discontinued power jet in the carbs. Have a look at the carburetor, air filter and cylinder pages in these.

https://drive.google.com/file/d/1eQNecw ... drive_link
https://drive.google.com/file/d/1r_37VT ... drive_link

Sorry for the confusion. It was all mine.