Hi All,

While changing the plugs on Saturday on my 450 it registered with me that the timing cover breather tube on the right hand side connects to the intake after the throttle body while the left hand side connects to the air filter before the throttle body. In my small brain I figure that the vacum on the right hand side must draw air (and oil vapour) down from the left bank and back up to join with vapour from the right bank to be burnt in the engine?
If this is correct how come this plumbing bypassing the throttle doesnt impact the idle speed? or maybe it does?

Cheers,
Gary

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Consider it a "controlled" vacuum leak.
The breather system should be kept clean,
as with all subsystems of the motor.
This is one of the easiest and first smog reduction systems

Thanks Brian, makes sense. I presume the flow is restricted near the idle screw so it is controlled.