Join Date: Aug 2011
Location: Fowlerville, MI
Oil on the back side of the tb is from pcv sucking in oil vapor. Oil on the front side is from your breather tube spitting oil. If that happens you must be at full throttle a lot or have other issues causing blow by.
ANY oil vapor getting into the intake is getting into your cylinders. Oil causes carbon build up. If you can eliminate that, you can eliminate most of your carbon issues.
$100? maybe. But, if you can build one for around $20-30, I'd say its well worth it.
And, just about every single small engine I've torn apart, and most large ones, all have oil in their intakes. Mainly due to the breather system. Its inevitable to get some oil in your intake over time. The PCV system is drawing out of the crank case which is always flinging hot oil around in it self. Oil vapors build up.
With that said, heavy throttle will close off the pcv system and will cause some crank case pressure. In these engines, it finds its way through the breather line connected to your intake tube, past the tb, and into the intake. This will occur in the best condition engine.