PCV Valve

ELLIS · Feb 21, 2020

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PCV BREATHER CRANKCASE VACUUM NON RETURN VALVE

Has anybody used one of these valves and if so was it an improvement to reduce air pressure within the engine. Did it also reduce oil leaks.

peter12 · Feb 21, 2020

I use one but it’s difficult to tell. I have a slight head leak which I’m fixing. Leaked before and after fitting, sorry, not really helpful. I’m keeping it though as the research I did prior to fitting showed it was worth it.
In my opinion, better than nothing, cannot afford more expensive crankcase options.
I have had virtually no oil out of it, a little water, presumably from cold starting, not sure if that shows any issues!

kommando · Feb 21, 2020

Yes its an improvement but suffers at high revs when it stops responding, you need a reed valve to work through the full rev range.

New from XS650 (think you have to go to the Netherlands site )

Go to ebay and search for EGR valve in motorcycle parts and pick from the selection presented.

comnoz · Feb 21, 2020

That type of valve requires manifold vacuum to operate. It would not work properly on a Norton motor.

A brake check valve would be better if your looking for a cheap fix.

maylar · Feb 21, 2020

This is the one most of us use:

https://www.mikesxs.net/yamaha-xs650-reed-type-engine-breather-valve-pcv.html

I haven't had any oil leaks from the engine since using one.

Lineslinger · Feb 21, 2020

Mikes XS, different configuration?
I made the bracket and installed it behind the Z plate. Once the fit was checked I ran the oil lines. Functions well.

Tornado · Feb 21, 2020

Ive tried the pcv in OP's post. While idling if I placed a finger over the output opening inside the oil tank neck I could feel both a pressure pulse out and a suction in. So it really was not going in the positive direction only. Leaks not so well prevented. Went to a XS reed and now only feel positive pressure pulses and oil leaks gone.

rvich · Feb 21, 2020

There has been considerable effort demonstrating reed valves as the better solution. Preferably attached to the case.

I am a believer in the Comstock reed valve solutions.

lazyeye6 · Feb 21, 2020

To actually establish a negative crankcase pressure (eliminates most oil leaks), a reed valve is required. Cheap
solutions result in cheap results. I've hear the XS is an effective and cost efficient solution. I am running a
Comstock sump reed breather. While expensive, it also purges the sump of oil quite quickly.

PCV Valve

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