Oil Breather

FunkZ · #1 (**permalink**) 08-25-2008, 06:09 PM

I'm tired of my stock breather leaking oil, it seems to come out the small holes in the side. I see there's an aluminum billet unit from STM available in nice pretty colors but I don't want to spend that much. I guess I could upgrade to the 2000+ unit which I believe is the all-black plastic? Mine has a metal band around it I think. Anyway, before I go buy one, is there any other option that actually just eliminates the hose and underseat box altogether?

Desmomaniac · #2 (**permalink**) 08-26-2008, 01:31 AM

Quote:

Originally Posted by FunkZ

I'm tired of my stock breather leaking oil, it seems to come out the small holes in the side. I see there's an aluminum billet unit from STM available in nice pretty colors but I don't want to spend that much. I guess I could upgrade to the 2000+ unit which I believe is the all-black plastic? Mine has a metal band around it I think. Anyway, before I go buy one, is there any other option that actually just eliminates the hose and underseat box altogether?

my experience is the older stock valves eventually leak.

i've seen three STM valves leak.

i have the nichols breather on the 900ss, it's never leaked in the 9 years i've had it whereas the oem did. i still have the oem breather on my 01 S4 and it hasn't leaked yet.

if you install FCR carbs on the 900ss it will require you to remove the hose from the air box to the oil separator under your seat. i put my power commander where the oil separator was on the s4; good thing because my battery ruptured twice and would have killed the power commander otherwise.

i run a 12"-ish hose and breather filter on top of the breather valve on both bikes. the motor will burp oil occasionally and can coat the hugger, tire, and swing arm; seen it happen on bike that run just a breather filter on the valve without the tube. tube prevents it from splooging itself and allows it to drain back into the engine. ymmv.

FunkZ · #3 (**permalink**) 08-26-2008, 02:23 AM

Thanks for the info! I was going to ask about the K&N breather kit. So if I pulled the breather out altogether and just put the K&N on in its place it would still leak oil?

jpuck91 · #4 (**permalink**) 08-26-2008, 08:53 PM

I ran a K&N kit on my bike for about 4 yrs or so, started having a mystery oil leak issue so I switched back to the stock tube & catch tank setup. Turns out the leak was from one of the side covers that didn't have enough liquid gasket material in there... so no issues w/ the K&N set up at all. I run a STM breather valve on my bike too, wanted to replace the stock valve with a billet part. Haven't had a single problem with the STM.

I think Lightech (?) or somebody else makes a bit cheaper billet/anodized breather similar to the STM. No experience with it though.

Desmomaniac · #5 (**permalink**) 08-27-2008, 12:34 AM

i would not recommend removing the breather valve and just running a filter in its place. the breather valve serves a purpose to maintain negative crankcase pressures; the rest is mainly to address emissions requirements.

if you just remove the oil separator under the seat and leave the tube from the breather valve you may be fine, but the tube from the breather may be to short to secure it anywhere close by iirc. i mounted a longer tube to the breather valve that allows me to secure the filter behind one of my rear panels.

mounting a breather filter directly to the breather valve is inadvisable based on my experience. oil can and will splooge a significant amount out of the breather valve; hence the reason the oil separator volume is as large as it is. the last thing you want while tearing up the roads is to coat your back tire, hugger, and rear brake in engine oil imo. seen it happen.

carbon fiber reed valves found in the stm tend to crack/fatigue due to its nature of being a composite laminate of different materials. the thermoplastic reed in the nichols is better suited to temperature cycles and immersion in oil.

i added a close up photo of the 900ss... this set up hasn't leaked in eight or so years. note the filter is attached to the frame under the rear panel on top of the tubing.

Quote:

Originally Posted by FunkZ

Thanks for the info! I was going to ask about the K&N breather kit. So if I pulled the breather out altogether and just put the K&N on in its place it would still leak oil?

DuctchDuc900 · #6 (**permalink**) 09-01-2008, 07:47 AM

Quote:

Originally Posted by FunkZ

Thanks for the info! I was going to ask about the K&N breather kit. So if I pulled the breather out altogether and just put the K&N on in its place it would still leak oil?

Don't do this unless you like oil near your rear tyre! Yes, oil will leak through the K&N.