Engine breather

[duck-a-tye]

Hi
What do you guys run as a engine breather tube on Darmahs? Mine has the large tube off the plastic breather cap, which runs up under the tank, but nothing else.

Cheers Tomo

[garryc]

My piece of garden hose runs up under the back mudguard and is cable tied to ther frame

[abmartin]

Mine just goes open to the atmosphere as well since the under-seat collector for my bike is missing. I recently put a small air filter on the end of the hose but I'm not sure whether it actually serves a purpose.

Bruce

[wdietz186]

The filter on the breather is a good idea.The engine inhales thru the breather when the pistons go up the bores and exhales when they come down.On the stock setup which everybody has removed the breather was routed inside the air filter housing.The little flap thingy at the end of the hose in the housing was intended to stop the inhale part of the cycle and reduce positive pressure in the cases which will also push out oil at high revs.A reed valve or one-way valve from an automotive air injection system works great as a substitute and can reduce the potential for oil leaks.

[duck-a-tye]

I came across a crankcase breather on ebay sometime back, it was for old british bikes I think.

The idea was it caused a vacuum in the crankcase, not pressure. Is something like this ok for Dukes?

Tomo

[Lumpy]

Sounds very similar to the set-up that wdietz186 is talking about. It all comes down to making negative pressure in the crankcases and inhibiting oil leaks. Rather than pay good cash maybe go with wdietz186 idea and get an old PCV valve and mount that on the breather tube. These are a very basic non-return valve or one way valve and you could perhaps mount one in the breather tube in such a way that would allow the engine crankcase gases to blow out but not suck in. You could pick up one of these valves from an automotive wrecker for nothing or very close to nothing. Certainly got me thinking, I`m going to ditch the bit of rag cable tied on the end of the breather tube and bung in an old PVC.

[duck-a-tye]

an old pcv valve will be easy to find. and I've ordered a breather filter off Steve, so I'm covered both ways

Cheers
Tomo

[wdietz186]

If you use a pcv get the largest you can find and mount it so it is vertical as most use gravity as a closing method.

[stian buksa]

Anybody tested guzzino.com`s Baffled Aluminum Racing breather box ?

http://guzzino.stores.yahoo.net/albrbox.html

I wonder if this is even better than the K&N filter on the end of the hose...
Pricier though
Is it still necessary to put a filter/valve at the out end of the tank ?

[wdietz186]

If you want to get all fancy and hang bling on it go ahead.The catch tank is good for racing as most orgs. require one and constant high revs will tend to push some oil out but on the street a hose and a filter is all that is needed.

[Elliot]

There is a nice little K&N filter which fits directly to the breather stack. I think it is off a turbo blow off valve. Does away with the hose completely and stops sucking dirt off the rear wheel!