Monday, November 28, 2016

Crankcase breather system

I'll be honest, when I started this rebuild I knew a decent amount about engines and mechanical operations related to internal combustion engines, but not as much as I do now. I saw all of this black rubber tubing and hoses and wanted to find out what it was for and get rid of it if possible. First step was the OEM crankcase breather. If you don't know what its for, the breather allows "blow-by" gas to escape the crankcase. This is exhaust gas that contains unburned hydrocarbons. Blow-by occurs when the gas escapes the cylinders past the piston rings, and its common on every engine. The breather sits on top of the crankcase and vents the gas out into a breather tube, into a collector reservoir that catches oil mist, and then routes the gas back into the intake manifold via the air filter and throttle bodies to be reburned.

This is an EPA requirement, but let me point out two things here; the engine is designed to breath clean air, not partially burned emissions and gases. The other point I want to make, is that the oil collected in the reservoir under the seat, has nowhere to go. The PCV breather has a one way reed valve that prevents gasses or fluid from entering the crankcase. So that crap sits there in the collector box.
Once I got rid of that, I had to replace the factory breather valve with something decent looking and still had to vent the gas out somewhere. I decided to get a K&N kit designed for this; it has a hose and filter that goes on the end to catch the oil mist

TPO calls it a "remote" crankcase breather kit.Has a hose that allows you to 
vent out the back of the bikethrough a small K&N filter

I also bought a new breather valve from STM I oversleeved the black hose the kit came with in braided steel for looks, its pretty cool. The hose is routed under the seat and vents out the back of the bike away from everything.  

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