On Sat, 30 Jun 2007 16:03:28 -0400, Meat Plow
wrote:

On Sat, 30 Jun 2007 12:41:54 -0700, Oren wrote:

On Sat, 30 Jun 2007 14:55:09 -0400, "Stormin Mormon"
wrote:

The crankcase breathers I've seen allow air out of the crankcase
when the piston goes "down", or into the crankcase. When the
piston goes up, the valve closes. This maintains a very slight
negative pressure, and helps cut down on oil leakage.

Not a pro here, but I've always thought of the breather as the direct
method for un-spent/burnt gases to escape. During the intake air we
don't want exhaust fumes to enter the head.

http://en.wikipedia.org/wiki/Four-stroke_cycle

A clogged breather can prevent the escape of the gases and not vent
the block.

Breather allows the crankcase to breath since there is a lot of air moving
around on the non combustion side of the engine also. Like Stormin
mentioned it's an oil conservation thing.

I would not have considered it oil conservation so much. But I do know
not to run the engine without it :-))

I've just always thouht of ventilation as the most important function
of the crankcase breather.


My forte is 2 strokers though. Rebuilt my own durtbike motors down to the
last needle bearing. Used to race unlimited class (360cc and above) in
what they called around here a "Hare Scramble." No money in it or national
recognitions but it was a great way to break bones and the chix loved it
too (watch us race)


I had one 360. The cop finally had to ask. Is this the bike that
out-ran me the other night? No Sir!!


--
Oren

"I don't have anything against work. I just figure, why deprive somebody who really loves it."