Crank case breather

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mean gene

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Yes I know this has been beat to death But I found this cheap and easy PCV valve that fits perfectly in your Commando breather line between crank case and oil tank. Hose barbs are correct size. Mount vertically for best results! Also cheap!


Crank case breatherCrank case breatherCrank case breather
 
Will this act as a check valve to create negative crankcase pressure?
 
I guess it’s a spring inside it right?

Beauty of the reed valves is they‘re designed for that rapid and constant movement.

The spring may not be…
 
I guess it’s a spring inside it right?

Beauty of the reed valves is they‘re designed for that rapid and constant movement.

The spring may not be…
I decided to go this way.

 
Yup.
Mines the same , used i believe on the Yam XS 650
Works a treat, all but stopped a head gasket dripping on the exhaust
 
I had a valve a lot like that for a while. Eventually it got all clogged up with white emulsified oil. Then I removed it and went back to my stock breathing system (MKIII) which just has a hose connected to the oil tank. The trouble is if the valve is not right on or in the engine in cooler weather it won't get warm enough to steam off the moisture. It might work better if your riding is only on hot days. I plan eventually on installing a similar valve right inside the timing cover. I think with the heat in there it will work better.
 
I had a valve a lot like that for a while. Eventually it got all clogged up with white emulsified oil. Then I removed it and went back to my stock breathing system (MKIII) which just has a hose connected to the oil tank. The trouble is if the valve is not right on or in the engine in cooler weather it won't get warm enough to steam off the moisture. It might work better if your riding is only on hot days. I plan eventually on installing a similar valve right inside the timing cover. I think with the heat in there it will work better.
I like that idea.
 
On your bike you get much closer to the engine, or the source of crankcase pressure than this:

 
On your bike you get much closer to the engine, or the source of crankcase pressure than this:

That's a lot of money and I plan to have the check valve mod done. Why in the hell Norton didn't include a drain back valve is beyond me. Harley Davidson had them in the 1930s.
 
I had a valve a lot like that for a while. Eventually it got all clogged up with white emulsified oil. Then I removed it and went back to my stock breathing system (MKIII) which just has a hose connected to the oil tank. The trouble is if the valve is not right on or in the engine in cooler weather it won't get warm enough to steam off the moisture. It might work better if your riding is only on hot days. I plan eventually on installing a similar valve right inside the timing cover. I think with the heat in there it will work better.
Is this a common problem with the XS Reed valve?
 
Spring loaded. Creates negative pressure in crankcase. It works. Easily hid under seat. Correct size's for breather hose, cheap! Better then nothing if your not planning on pulling engine for rebuild or have the money for reed valve modification!
 
Yes, better than nothing while it works, but I‘ve read of spring loaded devices failing before.
 
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