Hose question

[Polishpower77]

'81 GS850G, I am in the process of attempting to swap my air box filter assembly for air pod filters, but was wondering, where do I run this hose (see pic) coming from the engine? It used to run directly to the air box, but now it has no where to go. Thanks!

[Crage]

That's the engine oil breather hose. I don't have an answer, but I'm curious too as to what people are doing.

[GateKeeper]

make an oil catch can for it, or put a filter on the end of it....

http://www.thegsresources.com/_forum/showthread.php?t=204218&highlight=oil+catch+filter

http://www.thegsresources.com/_forum/showthread.php?t=199160&highlight=oil+catch+filter

http://www.thegsresources.com/_forum/showthread.php?t=134986&highlight=oil+catch+filter

and I am sure there are many more.....

[Crage]

AH just run the hose into a beer can....

[Polishpower77]

Cool, thanks fellas, appreciate it. Into a beer can you say? Easy, I got tons of empty ones lying around

[Steve]

No, ignore all those guys, it HAS to be connected to the air box.


Since you will be leaving the airbox at home, you will need to get a REALLY LONG hose.

.

[Badooka]

Nice Steve!

[AJ]

That's your crankcase breather vent. A tiny bit of oil mist will go out through the line. You don't need a catch can. If significant oil comes out of it, you have a problem (usually worn cylinders/rings causing blowby, or you overfilled your oil). There is no need at all for those little filters unless you are running it back to your air intake. Just a marketing effort to make you buy something you don't need.

In the old days, that hose would run back, over the carburetors and down somewhere around the swingarm pivot a few inches off the ground. My old Honda 350 even has a special hole in the frame to position that tube. At some time in the ancient past (like when your bike was built), the EPA mandated that the hose be fed into the air cleaner box so the oil mist would sucked back into the engine and burned.

Since you are removing the air box, run it back so it falls near (and below) the swingarm like it used to do.

TIP: Cut the end of the hose at a 45 degree angle with the open end facing back. (It's not super critical that it be exactly facing back.) The 45 deg angle will make the airflow suck the gases out of the tube, whereas a straight 90 degree cut will make the airflow pulse across the tube end, sometimes pushing air back into the engine. This is how they do it on airplane engines.

[GateKeeper]

But the little filter looks sooooooo cooooooool.......

[IndianaJones]

While it may sound like a good idea to let the hose dangle, you may want to reconsider the filter. If the mist is enough to make even a single drip, the filter material will catch it.

[AJ]

While it may sound like a good idea to let the hose dangle, you may want to reconsider the filter. If the mist is enough to make even a single drip, the filter material will catch it.

Until the filter gets all gooey with oil and then it starts dripping too.

[GateKeeper]

Until the filter gets all gooey with oil and then it starts dripping too.

clean it, wash it, or replace it.....

more or less just like any other filter....

.

[AJ]

clean it, wash it, or replace it.....

more or less just like any other filter....

.

I think the filter is valuable on an engine that really needs it. The inline 4's barely breathe at all (see the latest Hayden Krank valve discussions in the Performance section), and what little flow outward is from blow by. In contrast, Harley engines move a LOT of air out of and back into the engine. Given that the HD engines suck air back in, a filter is needed. It isn't needed on the GS-4's.

Of course, I'm not opposed to a little bling and if it makes you happy.