Topic: CB750 crankcase breather lines where do they go.

[Garage_guy_chris]

Ok so im trying to finish things up on the build and im replacing the 3 breather lines that were never there. I figured out that the:

-small barb on the bottom of the oil tank goes directly to the small barb on the back of the transmission:
    > OK and hooked up

-Big barb on the top of the oil tank is a vent to atmosphere
-Big barb on the back of valve cover vents to atmosphere
    > Where do the 2 atmosphere ends of these hoses route and vent? Typically they would come out the bottom of the bike but there is no where to get it passed the swing arm /  back of engine?

[Davez134]

I thought they were supposed to go there too, but ran into the same problem. Not sure if this is correct, but here is my solution and it works. Comes out under oil tank. You can see the 2 gray hoses in this pic under the tank. Barely visible. I guess you could just let them hang behind engine too, just air and water vapor come out of those so should not ruin any paint finishes.



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[PeWe]

Look here: http://forums.sohc4.net/index.php?topic=99667.0
I have a K6, only one rubber hose to oil tank ,crank case.

The valve cover breather hose is routed as it was from the beginning but I found thicker hose replacing the old and hard one. 1/2" Oil/hot water hose for cars. Routed over carbs, going down before oil tank and out to the rear passenger footpeg aiming aaway from the tire, strapped on frame.