Breather function

[Cjbdvm04]

I've been doing a full (and correct) rebuild of my k301. Before starting I had no clue as to how this engine functioned. Thanks to this forum and everyone's gracious input I have learned SO much. One thing I still don't fully understand is the breather unit. I assume it has something to do with venting pressure in the engine but I'm not sure. It appears to be a rather complex contraption with baffles, reeds, filter, etc. Could someone dumb it down for me to help me understand its function better? Also, Kirk engines sells a "remote" breather that looks far simpler than the stock unit. Is it really as simple as it looks? Is it better than the stick unit? Thanks.

[cubs-n-bxrs]

All that is a fancy cover with a pipe thread and a 90 elbow screwed in instead of a louver in the cover. It's purpose is to vent the crankcase gases via hose below the engine instead of blowing it all over the side of a freshly painted up engine. I just did the same thing myself only with polished stainless and tubing.

[Oak]

Yep, what Kelly said. When the piston is on the down stroke the crankcase will build pressure from the piston coming down and the reed valve will release it and close on the up stroke, the filter thingy filters the oil mist out and it drains back into the engine. When you have an engine with worn out rings, the blow-by of the compression going into the crankcase will over power the breather assembly and you will sometimes have an oil mist coming from it.

[Cjbdvm04]

So that retro fit cover only replaces the original cove and the oil mist is simply redirected through a tube? The guts of the unit remain in there?

[IHinIN]

Originally Posted by Cjbdvm04

So that retro fit cover only replaces the original cove and the oil mist is simply redirected through a tube? The guts of the unit remain in there?

That's correct.