Question about 1995 Honda XR 600 R

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My 95 xr600r dirt bike leaks oil

What would make my 95 xr600r dirt bike leak oil out of the crankcase breather hose

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This hose should be connected to the air filter box.

It's for ventilation of the crankcase, much like the PCV (Positive Crankcase Ventilation) in cars. As the bike runs, the crankcase gets hot enough to vaporize some of the oil. And since there's always at least a little bit of combustion blowby in the cylinders, you get a bit of fuel/air thrown into the mix and an oil/fuel/air "atmosphere" in the crankcase, which isn't an ideal situation. So, when the hose is connected to the air filter box, it slightly vacuums off this atmosphere, letting the engine burn it and expel it through the exhaust.

If it's not connected to the airbox, the vapors can condense back to oil and just drip out.

If a lot of oil is coming out ("a lot" is hard to quantify), you could be getting excessive blowby because of a broken ring or cracked piston.

Hook that breather line back up to the airbox and unless the bike smokes excessively, I wouldn't worry about it.

If it IS hooked up, it or the airbox is cracked and needs fixing/replacing. If the breather line has somehow become plugged (mud-daubers are amazing at finding holes to makes homes out of), the pressure buildup could have split your vent line.

Posted on Jun 01, 2010


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