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Conan_'dale

Crank breather hose to airbox question

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On my 2000 WR 400 I'm looking to do the breather hose to airbox free mod. On the bottom of the air box there is a plastic outlet stub. There is a clear plastic (soft) cap and clamp. I assume this a drain of some sort.

Can I attach the breather hose to this or do I need to drill another hole with brass nipple as the directions indicate for the newer 450's?

Thanks! :)

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You should definitely drill another hole. The plastic outlet stub is at the bottom of the airbox and is the low point of the airbox where the water collects. If you hook you engine breather there and you start your bike after washing it, you could suck this water into the engine.

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Interesting question. I found out the hard way that the plastic tube is the air box drain. No one ever told me about that before. By the way, you need to cut the end of the tube so when you squeeze it, it opens, thus letting the water out of the airbox. Both my brother and I had a hard time crossing a very deep creek a couple weeks ago. He sunk his bike. Had he known of this drain, he could have just drained the airbox and not sucked so much water into his engine trying to start it. If you ride in much water, make sure you know where the drain is and that is it cut and usable. I have TT member KLX365 to thank for this info, he showed me the "light". He helped us alot that day. :)

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Thanks guys. You really helped me a lot today. This forum is :)

Black-n-blue, How do you like your carbon pipe?

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On my 2000 WR 400 I'm looking to do the breather hose to airbox free mod. On the bottom of the air box there is a plastic outlet stub. There is a clear plastic (soft) cap and clamp. I assume this a drain of some sort.

Can I attach the breather hose to this or do I need to drill another hole with brass nipple as the directions indicate for the newer 450's?

Thanks! :)

That clear stub hose is a drain, its clear so you can see if it has water/debris in it. I did hook my breather hose directly to it. But you must drain it for water after washing etc. You can add a "T" in the hose with those one way rubber drains and point it down. This will keep water out when crossing streams, but allow water in the air cleaner to drain right out. Or just add a second drain setup in the bottom of the box for the water drain.

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It would seem that it would be best to connect the breather hose up away from the bottom on the airbox. Not only water but dirt and dust settle to the bottom as well. I don't think you want that being sucked into the engine either. IMO. :)

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Would there be any reason not to run the breather hose to the filtered air side of the filter? I ran mine through the circular rubber with some brass connectors and washers and sealed with silicone. It has been solid for two years now.

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Would there be any reason not to run the breather hose to the filtered air side of the filter? I ran mine through the circular rubber with some brass connectors and washers and sealed with silicone. It has been solid for two years now.

Ideally, would be to use one of those crankcase breathers found in older GM carb'd engines inside the air cleaner. They have the hose nipple on them, you just drill a hole in the box, stuff the breather through it and hook the hose on the other end. This will keep air going into and out of the crankcase filtered

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Would there be any reason not to run the breather hose to the filtered air side of the filter? I ran mine through the circular rubber with some brass connectors and washers and sealed with silicone. It has been solid for two years now.

I would worry about oily fumes from the crankcase gumming up the carb. A better option would be to just put a small filter on the end of the hose inside the airbox.

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Black-n-blue, How do you like your carbon pipe?
I love it, power and looks are top notch :) . Noise is a bit of an issue, even with the quiet cap. :) I havent had it tested, but it thumps pretty loud.

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Dang it...

I was going to bid on one today on e-bay but the auction ended at 4:00. It didn't have a S/A anyway. It was a full system and the last bid was 298.00. I sprung for the Dr.D system. Hope it's a good one. :)

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I too agree with pjriss (Paul) about using the filter on the tube in the airbox. The drain should not be cut and left open. It is inviting crap into the airbox esp water and mud in the wet stuff and if you do any deep crossings you've just lowered the depth of water you can cross by about 12 inches. It is easy to open and remove to clean out and I remove mine whenever I am cleaning the airfilter and use a squirt bottle of truckwash and then water to clean out the airbox and the water runs out the drain hole into a little plastic cup I place under it. Don't be lazy fellas! Its a simple little tube to remove while cleaning. The crankcase breather should be run through in its own hole and a filter added. Make it from some foam sponge and cable tie it on with a bit of ladies stocking material. This zip tie makes it easy to clean as you just pull it off the end of the tube, wash it then get a new zip tie and zip it back in. Keep it high in the box to avoid the dirt and crap that accumulates down the bottom. Put a zip tie (not too tightly) on the tube immediately on the inside of the hole that is drilled for it and it keeps it from sliding out. Silicone around the tube to keep it water tight for those deep water moments.

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All the old chevy's I've worked on had just a tube that ran from the crankcase to the filtered air side of the main filter - no secondary filter as you described. Everything I've messed with is pre-1973 though.

Oily fumes would get sucked into the carb if they are vented into the air box too. I took a look inside my carb and no gumming after 2yrs, so I don't think that will be an issue anyway.

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Here's the kind of filter I'm talking about:

http://www.knfilters.com/images/cvfsb.jpg

Doesn't have to be a K&N, most auto parts stores have plenty of this kind of thing. If you have the top of your airbox removed like I do just lay the hose over the top with the filter on the end, dangle it down about half way and you're done.

The reason I would be concerned about gumming up the carb is that a WR or most any other motorcycle doesn't have a PCV system like a chevy and the carb has a slide, unlike a chevy. The crancase is generally in a slight positive pressure and most of the venting is out the hose, not in. Mine actually drips oil over time and my thinking is that oily vapors will get caught in the oil foam filter. I'm probably over thinking this...

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All the old chevy's I've worked on had just a tube that ran from the crankcase to the filtered air side of the main filter - no secondary filter as you described. Everything I've messed with is pre-1973 though.

Check again. Its possible it was removed, but it was there from the factory. Even on pre 73. The breather hose (opposite side of had the PCV) went to the air filter housing, the nipple it slid onto was actually part of the filter. It has held on to the filter housing with a horsehoe type metal clip. Dirt cheap. I will look into this setup.

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Check again. Its possible it was removed, but it was there from the factory. Even on pre 73. The breather hose (opposite side of had the PCV) went to the air filter housing, the nipple it slid onto was actually part of the filter. It has held on to the filter housing with a horsehoe type metal clip. Dirt cheap. I will look into this setup.

My '67 Chevelle didn't.

There was a PCV valve on the oil filler neck (front of the intake manifold instead of on the valve cover... really convenient not unlike the I-Force), and the breather went to a bung on the bottom of the air cleaner with a domed screen above it.

My '69 LeSabre went from the valve cover to the outer rim of the air cleaner housing and had a filter inside.

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Here's the kind of filter I'm talking about:

http://www.knfilters.com/images/cvfsb.jpg

Doesn't have to be a K&N, most auto parts stores have plenty of this kind of thing. If you have the top of your airbox removed like I do just lay the hose over the top with the filter on the end, dangle it down about half way and you're done.

The reason I would be concerned about gumming up the carb is that a WR or most any other motorcycle doesn't have a PCV system like a chevy and the carb has a slide, unlike a chevy. The crancase is generally in a slight positive pressure and most of the venting is out the hose, not in. Mine actually drips oil over time and my thinking is that oily vapors will get caught in the oil foam filter. I'm probably over thinking this...

plriss, VERY NICE!!! I'll be doing this tomorrow. Can't go wrong with more filters. Easy to monitor/clean the system. Thanks! :)

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I think it might be better to "tee" the hose above the valve cover. Keep the current vent hose to allow oil to drip out, but run a second hose into the airbox.

The second hose would break the suction created when attempting to start the bike with the case submerged and keep water from being drawn in.

As far as dirt being drawn in contaminating the oil... I think most of us change our oil frequently enough so that this is not a concern.

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