No oil leaks..

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After 1200 Kms. spin about through Quebec then down through Adirondacks I am only cleaning off bug-splatts today. Belt primary drive,Yamaha XS 650 reed breather :) Machined in modern seals to tach drive shifter lever, kicker. Siezed opportunity to N.Y. State for oil change to VR1 with Zinc. Don't tell the Gov't as I believe Zinc is banned now here. Enjoy.
 
I have the xs650 valve an it filled the pipe that vented it to the oil tank with that stuff but pressure still managed to get past an steady stream of gas came out of oil tank breather.

Then it turned out to be rebore time an new valve guides to. Are you happy your engine is otherwise in good health an not breathing excessively? ?
 
FastFred said:
The oil is coming from the Norvil in line breather that I fitted (like a pcv valve). I took it off as there was that slimy white yellow oily goo coming out below the bike. It was full of the goo on the non return side of it that leads to the oil tank. I have cleaned it all out with petrol and it now all works fine. The end fittings have new ptfe tape to seal the threads. I think this would be better vented to atmosphere as soon after the valve as possible because currently it has to go through a reducer to get to the tank which is probably too much back pressure and more likely to cause condensation in the oil.
Click to expand...

IMO, these one-way breather valves should be mounted in such a way as to gravity drain the non-return side toward the oil tank. On the other hand, if doing so requires a long tube between the engine and the valve, the one way non- return function can be impaired. The best compromise is to mount the valve close to the engine as possible (shortest lead in tube), and clean the valve in petrol periodically (perhaps every oil change). as you did.

I know it sounds bizarre that the length of lead - in tube can impair the one way function, but very bizarre aerodynamics occurs in a tube carrying a fluid under a high frequency pressure pulse.

Slick
 
A few weeks ago i installed a one-way breather valve, a lever/ball valve on the oil supply line, an oil pressure gauge to monitor the situation, and a filter on the return line.
My engine seems happy and shows zero crankcase leaks thanks to no more wet sumping.
BUT...
I now have MORE leaks from the primary case and the gear box.
Coincidence?
Or just the gods of Old English Motorcycles playing games with me?
 
Yes that is just coincidence. A reminder that you are riding a classic....
Think I will clean every oil change.
 
As my grandfather joked, British Petroleum must have had a hand in the motorcycle design.

I've been running the cheapo flapper check valve in the vent line of my '74 right next to the timing case. They last about 1000 miles. I'll probably change over to the XS650-style this winter, but, so far, the floor's been clean!
 
The oil is coming from the Norvil in line breather that I fitted (like a pcv valve). I took it off as there was that slimy white yellow oily goo coming out below the bike. It was full of the goo on the non return side of it that leads to the oil tank. I have cleaned it all out with petrol and it now all works fine. The end fittings have new ptfe tape to seal the threads. I think this would be better vented to atmosphere as soon after the valve as possible because currently it has to go through a reducer to get to the tank which is probably too much back pressure and more likely to cause condensation in the oil.
Click to expand...
I have the same part, used for over 12 years and yes one of Les E's better parts. It's actually a Marine one way valve. Mine also fills with 'Mayo' and I dump the oil tank breather exit into a small bottle. No leaks from the valve stub adaptors though. I get about 50cc of water every 1500 miles or so and clean the breather the same frequency although I think it works fine regardless.
 
I have that Norvil brass one-way breather valve too, and have also found a lot of the emulsified oil goo on the downstream side. An easy clean. I'm curious though – I've seen the pros and cons of one-way valves in the breather discussed somewhere (sorry, can't remember where and presently lacking the mental stamina to go looking for it), and, while I'm happy at the idea of kind-of, sort-of, maybe creating a partial vacuum in the crankcase, or at least reducing condensation in there, I've seen that not everyone's convinced. Anyway, to the point of this post – I noticed the other day that, in the 1974 Norton brochure (http://www.classicbike.biz/Norton/Broch ... ochure.pdf), under 'Specification', subheading 'Engine', it says 'Positive crankcase ventilation from timing chest via non return valve to oil tank and air cleaner.' So my MK2A is supposed to have had one from the factory?! Or is this something that was planned but not carried out? I always thought it was an aftermarket fix ... So the point is, it appears that Norton considered a one-way valve in the breather to be beneficial ...?

p.s. Currently no oil leaks either, my bike doesn't mark its spot even when visiting my mum and stepdad, which is a severe test of Sod's Law! I even have the original automatic chain oiler fitted ...
 
FastFred said:
Went into the garage this morning and there is no oil under the bike, none! No leaks from engine gearbox or kick start and gear change lever. What should I fix?
Click to expand...

You better check your oil. :lol:
 
One thing I've not really had with my 750 commando is oil leaks ,I have a belt drive and a clutch push rod oil seal,I converted my gearbox outer cover, kickstart shaft / gear change shaft to take oil seals,I have a reed valve from an oxy acetylene torch breather on my timing cover and in all the years since built it has never actually leaked,I do get an oily mark on the crankcase join at the back of the motor but that's usually when I've been revving the hell out of it, cheers
 
Shameless bump on this:

I noticed the other day that, in the 1974 Norton brochure (http://www.classicbike.biz/Norton/Broch ... ochure.pdf), under 'Specification', subheading 'Engine', it says 'Positive crankcase ventilation from timing chest via non return valve to oil tank and air cleaner.' So my MK2A is supposed to have had one from the factory?! Or is this something that was planned but not carried out? I always thought it was an aftermarket fix ... So the point is, it appears that Norton considered a one-way valve in the breather to be beneficial ...?

I thought someone would bite on this! Is it settled that a one-way breather valve is beneficial? Did Norton ever fit one, to the Commando? I don't see one listed at Andover Norton, even for the MK3 ...
 
Never seen a factory one way breather, the closest is the MK3 separator but its not one way. The Norvil brass one way is a std plumbing one way valve and the ball bearing it contains will stop moving with the in and out pulses at high revs, hence why the favourite is the reed valve which will cope. Do an ebay search for EGR valve in motorcycle parts for suitable reed valves.

https://www.ebay.co.uk/sch/Motorcycle-P ... ve&_sop=15
 
kommando said:
...Do an ebay search for EGR valve in motorcycle parts for suitable reed valves.
Click to expand...

Leo Goff showed me how to use a EGR reed valve as a breather way back in the 1980s. There are better reed valves available now days and a couple actually use reeds that were designed for twin motorcycles.

You can make a Norton oil tight with no drips ever but you may still see a little stain from some of the joints when things get really hot.

You need the best sealer, the best gaskets and some oversize Orings.
 
I don't know if I have been blessed or been lucky as in 42 years of owning my 850 it has never leaked oil, I have had a gasket or two fail but were easy fixes but that was gear box gasket but on the motor its been very oil tight, I have installed a reed valve on the breather hose about 5 years ago as I run my breather hose into a catch bottle but I didn't put it on because of oil leaks.

Ashley
 
There are a bunch of threads here about reed valves, crankcase breathers, negative case pressure, wet sumping and evacuating oil.

The short and sweet as I understand it.

-The valve should be attached to the engine. Not only does it work better from a mechanical standpoint but it also warms the unit so that gases don't condense in it causing frothy gunk. If not attached, then closer is better despite it being easier to put one by the oil tank.
-Reed valves respond better than ball valves or PCV valves.
-I am pretty well convinced that the Comstock/CNW valve (which requires some machining to the back of your case) is the best way to go.
-There have been some adaptations for reed valves off the timing chest which can be achieved without pulling the motor.
-Ludwig probably deserves a blue ribbon for "best adaptation".
-At one point Comnoz had a reed valve that screwed into the sump plug in the 850 case. I don't know what happened to that idea or whether it is still available.
-No matter how good it is, it won't solve oil leaks caused by poor gaskets or seals, poorly prepped surfaces or warped parts.

Here is a vintage thread on the topic:
one-way-breather-valve-differences-t5929.html

Russ
 
Dorman reed valve (for brake vacuum booster) installed next to timing case in original breather hose.

No oil leaks..

They last me about one season, but do a bang-up job at keeping the rocker box covers from weeping without resorting to any fancy gaskets and/or sealants.

Nathan
 
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