Reed type PCV Valve

mcns · Dec 22, 2009

I just ordered the pcv valve from mikesxs650 to replace the motormite one I have in now.

Two things I am wondering about is I read somewhere to keep as far away from the engine as possible(which never made sense to me)
The other is to make sure it is solidly mounted. Can someone point out why this is. To me it would seem to work either way.

cheers

JimC · Dec 22, 2009

Actually, you want to mount any PCV valve as close to the engine as close as possible, according to the research done by Jim Comstock. The valve from Mike's XS is rather heavy, hence the solid mount.

swooshdave · Dec 22, 2009

JimC said:
Actually, you want to mount any PCV valve as close to the engine as close as possible, according to the research done by Jim Comstock. The valve from Mike's XS is rather heavy, hence the solid mount.

One of the things that I would want to check to see is if there was a way for oil to drain from the XS valve back into the engine. For example I believe the Ducati valve has small holes for the oil to drain (there shouldn't be much) back to the crankcase. On the BMW it appears to vent from a chamber in the crankcase so oil may be less of a problem. I don't know if this is an issue with the CNW setup.

Whatever solution I end up using I'll be sure to pull the breather and check for excessive oil.

Hortons Norton · Dec 22, 2009

Unless you are venting straight out and not to the tank I don't think there would be enough oil to worry about, Unless you had large amounts of blow by. Both of my bikes have the XS650 reed valves mounted as close as I can get them and they seem fine. The further away they are the less effective they are. Chuck.

chasesa · Dec 23, 2009

Chasesa, you have the same set-up as I did (71 motor) which means you already have a timed breather built in to the end of the camshaft on the drive side.
The problem some with that set-up is air can only escape through 1/4 hole, when I bought my 71 it was a rolling basket, so when I split the cases I drilled two holes in the timing side, then exiting where the 850 does and completely blocking off your exiting breather.

Now, I am really confused.

Can I install a PCV valve on my 1968 Commando, or not. If so, where should it be placed?
Stephen

swooshdave · Dec 23, 2009

chasesa said:
Chasesa, you have the same set-up as I did (71 motor) which means you already have a timed breather built in to the end of the camshaft on the drive side.
The problem some with that set-up is air can only escape through 1/4 hole, when I bought my 71 it was a rolling basket, so when I split the cases I drilled two holes in the timing side, then exiting where the 850 does and completely blocking off your exiting breather.

Click to expand...

Now, I am really confused.

Can I install a PCV valve on my 1968 Commando, or not. If so, where should it be placed?
Stephen

You can also add something, the real question is do you need to? Is the engine leaking oil anywhere it shouldn't? Do you ride the bike hard?

My guess is that with the Combat in 72 they knew that the bikes would be ridden even harder and needed better breathing than the timed breather could provide.

chasesa · Dec 24, 2009

I have a small and very annoying leak from the bottom of the timing cover. I will try again this winter to replace and silicone a gasket into place. Other than that, no leaks of consequence.
Stephen

mcns · Dec 24, 2009

A norton commando timing cover gasket should not require any silicone, just clean surfaces with brake clean and install.

cheers.

pete.v · Dec 25, 2009

The PVC from Mikes XS is a great unit. The inlet fits the hose coming from the engine, but the output is to big. I pulled the output pipe out of the pvc with not much effort. With no machining required, I tapped it with a 1/4 pipe tap . A 3/8 barb to 1/4 pipe fitting was applied. Cause this is a 90 degree application, I attached it at the top of the oil tank and came straight to from the vent connection tube on the oil tank. Looks very proper and works like dream.