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snowman02

Breather Tube

11 posts in this topic

First of all Thanx to all in response to my carb problem.

I am not sure if I am just worrying to much, because of uncorking this bike or if I really do have a problem here. I ran my bike (02 WR426) around the yard last night. It was running for about 20 min. went through all the gears a couple times. After I turned the machine off, oil started dripping out of the breather tube (tube hangs down in stock position, have not placed it in air cleaner as of yet). After all said and done, it left a spot about 3" in diameter on the garage floor. The oil level is fine. I am going to change the oil and filter tonight. Is this leaking normal or should I worry??

I feel stupid :banghead: asking questions of this nature, but I am new to four stroke world. My last bike, currently selling is a 82 IT465. :banghead: So far I love this WR. Can't wait to hit the desert in it this weekend. Thanx All :lol:

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Yes it's normal for the 426 to drip some oil from that hose. That being said mine only drips 4 or 5 drops :banghead:

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I've got a real dumb question on this topic. Is it normal for a fair bit of air to come out of the breather hose at idle? I know its called a BREATHER hose, but i accidently stuck my finger near it recently and was surprised by how much air was coming out.

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That's basically air that is blowing past the piston rings. The older the rings, the more the air.

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That's basically air that is blowing past the piston rings. The older the rings, the more the air.

Not always true, my 03 450 did it when new. It may get worse when blow-by increases but when that big piston moves down the air has to go some place.

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Not always true, my 03 450 did it when new. It may get worse when blow-by increases but when that big piston moves down the air has to go some place.

Hi,

When your bike had new piston rings they did not seal cylinder as well they do after good brake-in period. Problem is that synthetic oils to day are way too slippery for piston rings to break-in easily. This causes piston ring to move on top of the oil and not really sealing cylinder like it should. Which causes a lot of by pass fuel to the oil and excessive breathing thru hoses. If you have anyone who you know who races high performance cars ask them. This has been a problem over there until they started to do break in periods with mineral oils again.

Timo Mc

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As the piston moves up and down in the cylinder, the crankcase air volume is constantly changing and air moves in and out of the breather tube, this is normal. Visible oil vapor puffing out and a lot of oil drippage is not normal, this would be an indication of blowby. The breather tube is a two-way passage for dirt, dust and other contaminants. I run my breather tubes up high in the frame and install vent filters. This keeps out crud and greatly reduces the possibility of water getting in the crankcase in deep water crossings. :applause:

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I've got a real dumb question on this topic. Is it normal for a fair bit of air to come out of the breather hose at idle? I know its called a BREATHER hose, but i accidently stuck my finger near it recently and was surprised by how much air was coming out.

Yes, that breather hose is hooked into the crankcase, so you will feel air being sucked in and blown out as a direct result of the piston moving down. All this is being done by the underside of the piston, not the top. Some "blowby" will make its way down in the crankcase areas, and is normal, excess will be noticeable. So technically, that hose not only blows, but it sucks! :applause: Same reason in deep water, it will pull water into the engine.

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My YFZ 450 (Hi perf.) will blow out about half a quart of oil in a 4 lap moto. The engine builder said some engines do ? Not sure Why ??. Leak down test is good and there is no smoking at all. He suggests an air-oil separator. I guess the stock one sucks. Any Ideas ??

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Toyota Tech has it right synthetic oil or mineral oil if you have oil on the rings thay are sealing better than not having oil period. the breather hose is connected to the valve cover with a baffle to keep the oil in the motor crankcase pressure really crankcase air volume increases and decreases as the piston travels. you need to find out exactlly howmuch oil is in your motor I suspect you have too much search the service manual and this site for checking oil level. but first do an oil change and put only the factory recommended amount in the see where that reads on a warm engine.

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