Crankcase breathing - Ventilation

[ducinthebay]

Been doing a bit of reading on what to do with the crankcase breather and ventilation.
What is apparent is that you need to;
- Allow the pulses of air/vapor out of the engine.
- Allow the condensed oil to return to the engine, or catch it in stylish beer can. (actually advised since it has a lot of contaminates in it already)
- Keep a filter on it so you don't suck dirt back into the motor.
- and most important, have a one way valve on it to keep the pressure in the motor lower than atmosphere.


Mine, like many, had all of the plumbing removed along with the carbs and airbox. In acquiring spares, I have the original reed valve, but its huge. I also have the original condensation bottle, the blow molded bottle that fit under the electronics and around the shock. Unfortunately, I have an aftermarket shock,
so the bottle no longer fits.

Our engines have a straight through breather, and the most common modification is to simply put a filter on a hose.

Anyone done anything else to the breather system?

Cheers,

[jale28]

Hi,

I bought newer plastic case Ducati breather and have turned it to smaller diameter. http://cgi.ebay.com/ebaymotors/DUCATI-O ... 1c1e3fbf2a
So it now fit to replase the original hose connector in crankcase. It's connected to original bottle.

[ducinthebay]

An few articles to read and spark some debate.

http://www.ducati.ms/forums/56-superbik ... valve.html
and the self professed expert on crankcase ventilation;
http://www.britcycle.com/products/bunnb ... rticle.pdf
http://bunnbreather.bigblog.com.au/index.do

From what I can gather so far, the best setup for the Paso / Sport;
- use the stock fitting on the motor, as it has no reed valve.
- Use the stock breather box that came with your bike, or make one of considerable volume. More rigid is better. Same goes for the hose you use. It adds crankcase volume, and helps separate the oil out.
- add a good reed valve to the outlet of the box to create a negative pressure in the box, and likewise, the crankcase.
- Vent to atmosphere, not your airbox, as there are many noxious elements that you really don't want to re-introduce to your intake tract.

I don't have a good countermeasure for make up air just yet. I am considering using the Bunn system parts. Stay tuned.


After reading all of this, I now understand better why it is important to change your oil regularly. Lots of water and acids build up in the oil, especially if you go for lots of short rides. Your oil absorbs lots of crap. A proper breather system will reduce the amount crap the oil will absorb and lead to longer engine life, and higher performance.

Cheers,