Breather Valve Fixes Oil Leaks

In 2001 Alan Goldwater originally wrote about his 850 Norton developing new leaks around the pushrod tunnel joints as it aged.
I understand that the original artical can be found at in a revised from an article in INOA Norton News #124, although I have not read it.

< http://www.inoanorton.com/docs/BreatherValve.pdf >

Alan suggests installing the "Motormite/HELP #80190 brake booster valve" about midway up the large breather hose.


Has anyone tried this "fix"? Comments - including sending me to any exsisting threads on this topic.

The Motormite/HELP #80190 was my first try and it worked ok. Then found out about MikeXS unit. These are really good and have become so popular that I am sure Mike has sent his first born to Yale.

http://www.mikesxs.net/product/15-0677.html

See part number 46. http://www.oldbritts.com/1973_g16.html This is a reducer in the breather line. This is perfect as Mikexs pcv unit has these same size fittings. You can literally separate at this point, remover the reducer, pop on the valve so that it forms a right angle junction directly to the line that continues to the oil tank. No need to mount, it hangs just fine. I kid you not!

pvisseriii said:

You can literally separate at this point, remover the reducer, pop on the valve so that it forms a right angle junction directly to the line that continues to the oil tank. No need to mount, it hangs just fine. I kid you not!

Click to expand...

+1000

My bike pisses oil out of seemingly everywhere. With the XS650 valve installed it is manageable.

My biggest problem is not the lack of information to rebuild my '73 x 850 ... but a decided overwhelming mountion of good info to absorb! OldBritts is becoming a very useful site for me. Thanks pvisseriii.

I think mine was off a Japanese car :

I'm doing Mies XS thing at the moment. Didnt someone advise to put it as close to the timing cover as possible?

speirmoor said:

I'm doing Mies XS thing at the moment. Didnt someone advise to put it as close to the timing cover as possible?

Click to expand...

I believe the issue has to do with condensation. With the unit close to the motor, it is incline to warm up better than up top. The casing of the valve itself heats then cools more rapidly than the hoses. With the breather coming off of the timing cover, this is a good thing to do but not necessary. Getting the bike, and subsequently the oil, good and hot is what is needed to avoid the whitish goo.

I think the other aspect is the action of the valve itself. Being close to, or as some have done, mounted directly to the case, the action is more efficient.

Warning, the statement below is my own opinion of which I have yet to find agreement. If you do not agree, then do not read. :lol:
On the early 73's and 72 cases with the breather coming of the bottom rear left, I feel oil may effect the function of the reed and may not work as intended to a degree. I am not saying it will not work there, just not as well as if it were mounted a little up from the sump level. My analogy is that of playing a saxophone with a mouth full of 50w.


All of that being said. I machined a set of late 72 case to except a breather valve at the timing cover. Many have adapted a plate on the early 72's for this purpose. I have also done the crankcase mod, again of which there are mixed opinions.

If one is good, is two better? I am at this time running both the timing breather valve AND a Mikesxs unit up off the lower crankcase, mounted at the right angle level. I think I do this simply because i can. I had a cap on the lower case but decide to give it a try. Why not? No big whoop!

Well its as near to the timing cover as possible at the moment. The right angle of the piece though makes for weird breather hose routing when placed so low.Its function over form at the moment.

pvisseriii said:

Warning, the statement below is my own opinion of which I have yet to find agreement. If you do not agree, then do not read. :lol:
On the early 73's and 72 cases with the breather coming of the bottom rear left, I feel oil may effect the function of the reed and may not work as intended to a degree. I am not saying it will not work there, just not as well as if it were mounted a little up from the sump level. My analogy is that of playing a saxophone with a mouth full of 50w.

Click to expand...

Jim mounted his breather right to the case, if there was any oil being forced up during normal running he would have seen it. What does that do to your theory?

I have the screw-in, bottom-of-case-mounted Jim Comstock breather and it clears the crankcase of oil on startup up at least as well as the scavenge pump. This particular reed valve is perfectly happy playing its tune with a mouth full of 50w.

Whitworth Ranch said:

I have the screw-in, bottom-of-case-mounted Jim Comstock breather and it clears the crankcase of oil on startup up at least as well as the scavenge pump. This particular reed valve is perfectly happy playing its tune with a mouth full of 50w.

Click to expand...

The thought is that on the 72 (only) the oil may be flung at the back of the crankcase towards the breather. On your bike I wouldn't be a problem.

swooshdave said:

pvisseriii said:

Warning, the statement below is my own opinion of which I have yet to find agreement. If you do not agree, then do not read. :lol:
On the early 73's and 72 cases with the breather coming of the bottom rear left, I feel oil may effect the function of the reed and may not work as intended to a degree. I am not saying it will not work there, just not as well as if it were mounted a little up from the sump level. My analogy is that of playing a saxophone with a mouth full of 50w.

Click to expand...

Jim mounted his breather right to the case, if there was any oil being forced up during normal running he would have seen it. What does that do to your theory?

Click to expand...

I guess it supports it. If you do not see or have any oil coming from the breather of a 72, of which I see as somewhat inherently normal (the original can of worms), then air might not be passing throught either. Dave, didn't you yourself create a oil drain back hole in the unit just for this porpose?

Whitworth Ranch said:

I have the screw-in, bottom-of-case-mounted Jim Comstock breather and it clears the crankcase of oil on startup up at least as well as the scavenge pump. This particular reed valve is perfectly happy playing its tune with a mouth full of 50w.

Click to expand...

Yes, a differant ball game, not an issue for you, You're one of the lucky ones.

pvisseriii said:

swooshdave said:

pvisseriii said:

Warning, the statement below is my own opinion of which I have yet to find agreement. If you do not agree, then do not read. :lol:
On the early 73's and 72 cases with the breather coming of the bottom rear left, I feel oil may effect the function of the reed and may not work as intended to a degree. I am not saying it will not work there, just not as well as if it were mounted a little up from the sump level. My analogy is that of playing a saxophone with a mouth full of 50w.

Click to expand...

Jim mounted his breather right to the case, if there was any oil being forced up during normal running he would have seen it. What does that do to your theory?

Click to expand...

I guess it supports it. If you do not see or have any oil coming from the breather of a 72, of which I see as somewhat inherently normal (the original can of worms), then air might not be passing throught either. Dave, didn't you yourself create a oil drain back hole in the unit just for this porpose?

Click to expand...

The drain back hole was just to allow any oil trapped above the reed valve to drip back in. Let's say there is too much oil in the crankcase and I start it up. The oil will get pushed up pass the reed and into the oil tank. If I shut off the bike before this can occur then the oil can escape back to the crankcase. But this is an exception and only if the engine isn't ran long enough to clear the breather system (a few minutes).

Oil would come up the stock breather because all it was just an open tube. There was no control of the crankcase pressure. But with the reed valve once the excess oil, if there is any, and extra pressure have exited the crankcase all the oil will be scavenged normally. No reason for oil to come up the breather.

swooshdave said:

Whitworth Ranch said:

I have the screw-in, bottom-of-case-mounted Jim Comstock breather and it clears the crankcase of oil on startup up at least as well as the scavenge pump. This particular reed valve is perfectly happy playing its tune with a mouth full of 50w.

Click to expand...

The thought is that on the 72 (only) the oil may be flung at the back of the crankcase towards the breather. On your bike I wouldn't be a problem.

Click to expand...

I've only ever worked on my '74 so this is clearly an issue I am not aware of. I mean, thankfully not aware of! Carry on...

swooshdave said:

But with the reed valve once the excess oil, if there is any, and extra pressure have exited the crankcase all the oil will be scavenged normally. No reason for oil to come up the breather.

Click to expand...

Unless the crankcase has been modified and even if they have, oil does not scavenge normally on 72's. Again, I refer to the original can of worms. http://www.oldbritts.com/n_c_case.html

This is kinda a fun ain't it, Dave. Like the good old days. Sure beats those slanderous and abusive threads.

quote]

Unless the crankcase has been modified and even if they have, oil does not scavenge normally on 72's. .[/quote]

I have a combat breather on a 750. Read about scavenging issues and put the hose to a bottle to monitor. 7000 miles on and a number of high speed runs (1/2 hr at 6500 rpm) Never a problem or oil leak and just oil mist in the bottle. It can run a 1000 hard miles with no discernable change to oil level. Maybe I got a good one.

Nortiboy said:

quote]

Unless the crankcase has been modified and even if they have, oil does not scavenge normally on 72's. .

Click to expand...

I have a combat breather on a 750. Read about scavenging issues and put the hose to a bottle to monitor. 7000 miles on and a number of high speed runs (1/2 hr at 6500 rpm) Never a problem or oil leak and just oil mist in the bottle. It can run a 1000 hard miles with no discernable change to oil level. Maybe I got a good one.[/quote]

I want to run a hard 1000 miles!!! I am sitting around waiting for that damn conical seal!

acotrel said:

I think mine was off a Japanese car :

Click to expand...

Does it work well?
Acotrel can you recall what that breather was off.
I looked at Mikes breather and shipping to Australia was over $30. :evil: