pcv valves and oil leaks

JimC · Jun 29, 2009

Here it is.

plj850 · Jul 2, 2009

bigstu said:
I have just got an 1973 850 MK2a back on the road and would like some advice if possible from more knowledgable Norton folk than me.
I appear to have some oil leaks from my engine. This does not suprise me, as I seem to be quite adept at putting engines together that leak.
No 1 leak deposits oil on the leading edge of the primary drive cover, but is coming from somewhere close to the L.H. exhaust manifold. I can't really see any more than that...maybe the head gasket just under the exhaust?
No 2 leak seems to be coming from the small rocker shaft covers, with their multiple gasket/dodgy bits of tin.
No 3 leak seems to be coming from the the rear rocker adjusting cover, with its sigle nut fixing onto a cover that must act as a large diaphram spring?

Late in the day I know but 2. is just very careful assembly with flat covers and the important gasket (the first one with the big hole in the center) fitted with maybe a very thin layer of silicone sealant.
For 3. RGM do a set of Neoprene rocker box cover gaskets that work for me.

plj850 · Jul 2, 2009

bpatton said:
swooshdave said:

Ducati breather valves, but they are more like $80 or so, depending. Ironically the "trick" think for the Duc folks is to move the reed valve away from the engine and to the airbox. Unfortunately this works better for race motors but the posers don't care.

Click to expand...

There must be a reason be a reason why moving the valve works better, I can't figure it out though. There are some pretty remarkable gains to be had by getting the air out of the crankcase. One Commando racer said he was getting 5-6hp out of it. Appears to be a matter of pushing the air around. Formula One and NASCAR guys really work at it.

http://www.coloradonortonworks.com/cata ... e.asp#1713 This is cool, seems like it might be kinda wet, maybe.

Maybe a tad expensive for me...

I am trying my $15 XS650 valve.

swooshdave · Aug 30, 2009

fastback said:
I was going to order one too , but got too annoyed at paying $20 shipping for a domestic order a $17 part. Call me cheap - but it is more the principle of the matter. I told Mike that I so to. I have no problem paying for a part - just don't pretend it's "shipping"
:twisted:

Shipping from Florida is about $8 to Oregon. You should check the shipping from the Canadian location (if that's not "virtual"). http://www.xs650direct.com/

seaguy · Aug 31, 2009

I've been reading all these posts on the use of the XS reed valve with interest but I can't figure out where one would install this optimaly on a 71 engine. The only vent line I see on it is the one from the cam end on the left front. How about a hose fitting on the place where the tach cable goes since I won't be using a mechanical tach? What have other 71 owners done for this?

swooshdave · Aug 31, 2009

seaguy said:
I've been reading all these posts on the use of the XS reed valve with interest but I can't figure out where one would install this optimaly on a 71 engine. The only vent line I see on it is the one from the cam end on the left front. How about a hose fitting on the place where the tach cable goes since I won't be using a mechanical tach? What have other 71 owners done for this?

I believe that's a "timed" breather. A reed valve won't do much if your engine is left as is. Are you having specific pressure problems? Excessive oil leaks from joints/seals? If not, leave it alone.

maylar · Aug 31, 2009

Can someone give me ballpark dimensions fot the SX650 breather valve? From the pics posted in this thread it looks kinda big & klunky. I have a 3 phase regulator attached to the back of my airbox and there's not much room left in the battery compartment. The Motormite piece fits perfectly atop the oil tank, but alas I have oil leaking after only 1000 miles with it.

Thanks

Brithit · Aug 31, 2009

swooshdave said:
fastback said:

I was going to order one too , but got too annoyed at paying $20 shipping for a domestic order a $17 part. Call me cheap - but it is more the principle of the matter. I told Mike that I so to. I have no problem paying for a part - just don't pretend it's "shipping"
:twisted:

Click to expand...

Just ordered two XS breathers from Mike, and the total including shipping was $39.58. That's to a U.S. address. Been using a Motormite for years, and never had any problems, but I thought I'd see what these were about. I've got both of these new breathers mounted and they are working nicely. As were the two Motormites. I don't know about the rest of you, but I'm a hopeless gear-head, and if I can try something new for under $40, I thought, why not give it a go? Compared to thousand dollar carb conversions, and cartridge fork dampers, well, I'm channeling my inner Fred Sanford. Thought I would add that both my '72 Combat (with every breather and oil pickup mod) and my MKIII are both oil tight, with only the most minimal drips once in awhile. Major oil spewing, I don't like, but the occasional drip is no big deal.

zackybilly1 · Aug 31, 2009

I removed the mounting bracket and ground one of the ears off the valve and installed mine on top of the tank. Used stock hose from the timing cover and a short piece of hose from valve to filler neck. Worked so good, I bought two more for Triumph projects (known leakers).

Best mod you can make for the money.

Z

seaguy · Aug 31, 2009

I believe that's a "timed" breather. A reed valve won't do much if your engine is left as is. Are you having specific pressure problems? Excessive oil leaks from joints/seals? If not, leave it alone.

At the present time my engine is completely disassembled. If I have to drill vent passages now's the time unless the 71 is the only engine that doesn't make crankcase pressure. I was hoping that a 71 owner might chime in with a few pearls of wisdom.

pelican · Aug 31, 2009

would that xs650 valve work ok on an 850?

swooshdave · Aug 31, 2009

pelican said:
would that xs650 valve work ok on an 850?

Sure.

plj850 · Sep 12, 2009

pelican said:
would that xs650 valve work ok on an 850?

Just fitted one to my Mark II and it brought instant results one of the best and cheapest modifications I have done (16 euros).

seaguy · Sep 24, 2009

To complete the thread for readers Mat from CNW wrote me and said the 71 as well as the rest will benefit from the Reed Valve Mod. He didn't say where it goes , only that they could do it . I guess the timed breather didn't get the job done either.

swooshdave · Sep 24, 2009

seaguy said:
To complete the thread for readers Mat from CNW wrote me and said the 71 as well as the rest will benefit from the Reed Valve Mod. He didn't say where it goes , only that they could do it . I guess the timed breather didn't get the job done either.

It kinda like the difference between a piston port two-stroke engine and a reed valve one. For sake of brevity, let's just say in a vast majority of the cases the reed valve is more efficient.

Considering the size of the timed breather it doesn't seem like it can remove much pressure. But that's just a guess.

plj850 · Sep 24, 2009

seaguy said:
To complete the thread for readers Mat from CNW wrote me and said the 71 as well as the rest will benefit from the Reed Valve Mod. He didn't say where it goes , only that they could do it . I guess the timed breather didn't get the job done either.

The timed breather type is definitely a candidate for a PCV valve with a modified timing case or an expensive modified crankcase and PCV from CNW.

nomadwarmachine · Sep 24, 2009

zackybilly1 said:
I removed the mounting bracket and ground one of the ears off the valve and installed mine on top of the tank. Used stock hose from the timing cover and a short piece of hose from valve to filler neck. Worked so good, I bought two more for Triumph projects (known leakers).

Best mod you can make for the money.

Z

Pardon my ignorance, but I'm planning to do this modification to address the leaking problem I've recently developed, and I want to be sure that I do this right. Can somebody tell me:

1) Where on the oil lines going to and from the oil tank do I mount the XS650 breather? Do I mount it to #21 or #16 (or #47) on the following schematic?

http://www.oldbritts.com/1973_g16.html

2) Is there any reason I cannot use the breather valve on the return line along with an anti-wetsump valve on the feed line? I'm planning to order one of these from CNW.

Thanks!

swooshdave · Sep 24, 2009

nomadwarmachine · Sep 24, 2009

That's the schematic, but which hose do I cut and mount the breather onto?

chris plant · Sep 24, 2009

hi nomad,#47

pcv valves and oil leaks

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