Crankcase Breather Chamber or Separation Box

[Cadmandu]

 I was wondering if it would be okay to pull off the hose that runs up to the air box. This is just dumping dirty bypass gas into the carb right.

[John Luttrell]

I replied to your PM on the Dark Side Forum, but the answer to your question is no.  The Positive Crankcase Ventilation System uses the negative pressures in the air box to pull the blow by gasses from the crank case, where the unburned hydrocarbons are mixed with the air/fuel charge and reburned in the cylinders.

There are two reasons I'd leave it stock; the first is that an over pressure condition in the crank case can blow oil past gaskets and seals.  The second reason is, if you allow it to vent to the atmosphere, what little bit of oil that blows out of the hose will get all over your bike, making a mess.

[Cadmandu]

Thanks John,

  Is the V4 MuscleBike and the darkside the same place? I have been trying to figure this all out with bits and pieces of info here and their. What do people do with crankcase ventilation filters?

http://www.denniskirk.com/jsp/product_catalog/Product.jsp?productId=p301754

Thanks, I will take your advise and put it all back like it was.

[John Luttrell]

A lot of the old bikes and some of the custom made choppers do not have a PCV system; on those bikes you need some kind of filter to catch the oil that vents to the atmosphere with the blow by gases.