The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: stevejs on 27.11. 2018 15:59

Title: What is it (breather on tappet cover?)
Post by: stevejs on 27.11. 2018 15:59
Any of you clever people know what this is for? It's on the inlet tappet cover on my 1954 A7SS. Some kind of breather??
Title: Re: What is it (breather on tappet cover?)
Post by: Topdad on 27.11. 2018 16:13
yep , it's a breather fitted in the hope it helps fight oil leaks ,just read an article which said it can do the reverse ,I've done one on my inlet cap and honestly cant see any difference .cheers Bob
Title: Re: What is it (breather on tappet cover?)
Post by: cyclobutch on 27.11. 2018 16:55
Got one on my A10. Roger at Cake Street blocked it off when he rebuilt my motor - I think he took a dim view.
Title: Re: What is it (breather on tappet cover?)
Post by: Black Sheep on 27.11. 2018 17:27
Physical evidence of desperation.
Title: Re: What is it (breather on tappet cover?)
Post by: berger on 27.11. 2018 18:57
I have not been to the pub, that sort of breather on the inlet can pull extra air down worn valve gear and confuse you when setting up a carb
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 27.11. 2018 19:01
G'day Steve.
As said it's for a breather. I have one on my Cafe with a Bunn breather (one way valve) and another on the engine breather behind the primary. Fresh air goes in at the top and smelly air comes out the bottom. Sort of like us!
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: BSA500 on 27.11. 2018 20:17
Mine had the effect of clearing the creamy oil emulsion from the rockerbox. Didnt matter how hot the engine got it was always there,not now *smile*
Title: Re: What is it (breather on tappet cover?)
Post by: bsa-bill on 27.11. 2018 22:17
Quote
the creamy oil emulsion from the rockerbox

Never seen any of that on my bikes - on Mini's I had oh yes
Title: Re: What is it (breather on tappet cover?)
Post by: duTch on 28.11. 2018 02:45
 
Quote
.Mine had the effect of clearing the creamy oil emulsion from the rockerbox......
  Generally means a presence of water/ moisture- I had a heavy presence of that recently in my Ute slow head gasket leak (obviously won't be a cause on a BSA, but .ca be sucking it in through the covers., ore just condensation buildup if not often used...

 
Quote
....Fresh air goes in at the top and smelly air comes out the bottom....

 I always figured the breather just expels excess buildup of the air already in there by default.... and doesn't need any extra....*dunno*/ *conf2*
Title: Re: What is it (breather on tappet cover?)
Post by: hdawson on 28.11. 2018 06:02
I have always wondered where the breather is located on my A10. Could someone enlighten me please.
I assume it is working as I don't suffer (excessive) oil leaks but I have been told by very knowledgeable persons that my engine would benefit from an extra fitted breather. What is the general opinion on this one?
Cheers, Hadrian.

Title: Re: What is it (breather on tappet cover?)
Post by: Black Sheep on 28.11. 2018 06:23
Nah. The designers did well enough. If your bike's breathing is inadequate, something's not right. 
Title: Re: What is it (breather on tappet cover?)
Post by: duTch on 28.11. 2018 07:38

 
Quote
I have always wondered where the breather is located on my A10. Could someone enlighten me please........

 The exit hole is under the boss of the left end of the camshaft,  behind the chaincase and  in front of the magneto end cover
Title: Re: What is it (breather on tappet cover?)
Post by: BSA_54A10 on 28.11. 2018 20:33
Nah. The designers did well enough. If your bike's breathing is inadequate, something's not right.

Actually this is one time when they did not .
The factory breather really only works well up to 1/3 throttle, barely works to 2/3 throttle and works backwards over 2/3 throttle.
Rex did a lot of work before he handed the project over to Auckland University where they did extensive testing revealing the above.

Now the caveat to this is the bulk of the time we ride at 2/3 throttle or less so it will do, although it could be better.
Weather it is worthwhile to muck around with breathing depends very much on the rider.
If you are WFO type of rider ( ie Musky ) then it is worthwhile and will substantially reduce leaking & oil burning.
On A7/10's proper breathing will end the infamous rocker box leaking that bedevils a lot of owners.

The idea of creating a partial vacuum in the crankcase comes from the days of long stroke engines that had no oil seals and had a rev ceiling in the order of 5000 rpm.
Thus the engine was designed to perpetually suck air in through all of the slingers & blow it out the breather past an unsprung almost one way valve.

Crankcase venting is every bit as complicated as induction breathing and exhaust tuning.
As such it is very difficult to design  system that will work properly all the way from idle through to valve bounce.
The through flow design with check valves is the only system that has the ability to work over the entire rev range.
No mechanically timed system can work properly over the entire rev range because air has mass and therefore there is a latency and momentum effect which gets more pronounced the higher the revs.
On the A 10 tested near 1.5 Hp is gobbled up by the ineffective breathing system at peak revs.

Now back when the bikes were new, leaving a puddle of oil on the ground after a good "high spirited" ride was acceptable .
However leaving a pool of oil when at idle on the showroom floor was not.
Thus a breathing system that works best just off idle.
Title: Re: What is it (breather on tappet cover?)
Post by: Greybeard on 28.11. 2018 23:09
Well, you live and learn!
Title: Re: What is it (breather on tappet cover?)
Post by: Black Sheep on 29.11. 2018 06:28
I'm still not going to mess around with the breathing on my bikes. 46 years of good service and hardly an oil drip is good enough for me.
Title: Re: What is it (breather on tappet cover?)
Post by: BSA_54A10 on 29.11. 2018 08:53
I'm still not going to mess around with the breathing on my bikes. 46 years of good service and hardly an oil drip is good enough for me.

Oh so you got the good one did ya ?
Title: Re: What is it (breather on tappet cover?)
Post by: cyclobutch on 29.11. 2018 08:57
Mine has developed a slight leak from the rocker covers this last year so is due some re-sealing over the winter.

Title: Re: What is it (breather on tappet cover?)
Post by: hdawson on 29.11. 2018 09:45
I've seen some bikes with an additional breather drilled from the top of the crankcase and been told that the engine 'spins more freely".
Whatever that means.
I think it would have to have significant benefits to mutilate my case.
Title: Re: What is it (breather on tappet cover?)
Post by: Black Sheep on 29.11. 2018 10:06
"Oh so you got the good one did ya ?" Yes. 2 in fact.
Title: Re: What is it (breather on tappet cover?)
Post by: JulianS on 29.11. 2018 10:17
Like Black Sheeps bike my A10 keeps the oil in - and it gets used good and hard and often.

Back along Webco in the USA and Eddie Dow in the UK produced finned rocker covers with a breather outlet. Tried them but not convinced they had either positive or negative effect on breathing. A simple experiment with a freezer bag sealed to the rocker breather tube showed that more air was sucked in than expelled.

(Damaged) Webco rocker covers below.
Title: Re: What is it (breather on tappet cover?)
Post by: Sluggo on 29.11. 2018 10:46
I will not argue with the "Stock is good enough" crowd, or the "Factory knew best" as if it works for you, then thats all that matters.  But Trev is correct, There is a lot on these bikes that can be improved.  Breather is one of them.   
No lack of testing on other motorcycles and cars and science and technology have evolved since the 1950s,, Point in case, what was thought to be ideal Port and Polish techniques on intakes and cyl heads has  changed 180 degrees.  (Smooth & polished is not the ideal anymore)

Many other brands tend to have their own ideas (Dont go arguing with the Norton nutters!)  But here is a design that has proven to be ideal.   Buell came out with it on production machines and most modern brands now use a variation or something similar, Although, MOST run the venting INTO the intake as this is now mandated in most jurisdictions.  I have updated my older V twins to this Buell type spec with their PCV valves.  That Eric sure did know a thing or 2 about performance engineering.

In high RPM applications, there is proven DYNO verified performance gains with a driven air pump evacuation system, Not totally practical on a old BSA... but the test results are out there if you care to review..With such a small engine a pump design would benefit it, But the HP & Torque would not be that big of a number but the leakage problems would go away for sure..

Here is a typical Auto system... See: https://www.jegs.com/i/Moroso/710/25900/10002/-1  (no pump)
                                                   
 https://www.ebay.com/p/Moroso-22640K-Original-3-Vane-Vacuum-Pump-Kit/15017008969?iid=172256694429&chn=ps                   (With vacuum pump)

I have seen over the years many dyno tests and race car engines can see between 15hp to as much as 40 HP using a vacuum pump design,
Here is a Big Block V8 test (Many youtube videos out there as well)
See: https://www.hotrod.com/articles/ccrp-9903-moroso-vacuum-pump-test/

"  Peak to peak, the pump in its as-run configuration on this engine was worth about 14 lb-ft of torque and 10 hp over the no-system configuration. It was also up about 17 lb-ft and 6 hp compared to the exhaust evacuation setup."

More on the tech,,,,See:
https://www.dragzine.com/tech-stories/tech-how-external-vacuum-pumps-free-up-horsepower/

Title: Re: What is it (breather on tappet cover?)
Post by: bsa-bill on 29.11. 2018 12:24
Correct me if I'm wrong but to some extent will the engine breath via the oil pump and the breather on the top of the oil tank
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 29.11. 2018 18:56
G'day fellas.
 I doubt that Bill.
My use of the Bunn system was wholly to do with performance and it did that very well. The motor spins much quicker (quicker throttle response) and it's expelling all the burnt and unburnt fumes (that can eat seals). A much welcomed side affect was the reduction in oil leaks. The swing arms rockerbox leak isn't as bad but will always be prone due to the stupid head steady design, plungers and rigids don't suffer as much due to the steady below the rockerbox. That's a different subject that has been discussed before.
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: bsa-bill on 29.11. 2018 19:05
Well don't like to boast but at this moment in times my Flash is oil tight
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 29.11. 2018 19:07
 *shh* don't let her hear that!
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: BSA_54A10 on 29.11. 2018 20:41
The simple physics of it is compressing air requires energy
Sucking air out to make a vacuum or just lower the pressure requires energy.
Moving air requires energy.
Of the 3, just moving it requires far less energy than the other 2.
So a breather that is a flow through design will sap less power from your engine than one that tries to run a low pressure in the crankcase.

What we always need to remember is a lot of the design work that was done pre-computer age was suck it and see because they knew the theory & principles but lacked the measuring & calculating power to optimize .
Now days we can map the flow of oil inside the engine by measuring the difference in the heat on the outside then correcting for radiation & conduction.
Back when A series engine were being designed, the best they could do was cut a hole in the engine and shove a lump of pyrex glass in there and hope to see what was happening before the window got too dirty to see through.

So a breather that was good enough to prevent the entire contents of the oil tank being blown out the overflow or exhaust on one model , got transferred to the next model.
Also research cost money, lots of it, so winning races or running for a long time , things that were major selling points get the money spent on them.
Back in the 40's & 50's a lot of the roads were not sealed kerb to kerb, if they were sealed at all so oil dripping from a motorcycle was not considered a problem, or even a selling point till the Japanese made motorcycles that were bone dry underneath.

Also as I have tried to illustrate, fitting a breather that actually works is a lot more complicated than just making a hole and shoving any old pipe on it.
Thus a lot of the kits of the day did more harm than good.
HD never solved their oil leaking problems till they got Rex on the job and started fitting his modified breathers as standard.
The same goes for RE

Title: Re: What is it (breather on tappet cover?)
Post by: Black Sheep on 29.11. 2018 20:56
Enfield 250 singles had a very small one way crankcase breather that was almost adequate (mine was oiltight up to 52 mph) but when they went for a bit more performance with the Continentals they opted for a great big drainpipe open to atmosphere to do the job. It seemed to work so presumably they drilled the hole in the right place and made the breather pipe the right length. Presumably it freed up a little bit more power at high revs - just before the con rod snapped.
Title: Re: What is it (breather on tappet cover?)
Post by: kiwipom on 30.11. 2018 03:02
Hi guys, difficult to see how sucking air in and blowing air out can require energy
as the piston going up and down does that normally anyway, `pulse` fuel pumps
do that on the likes of some lawn mowers/atv,s and the like, cheers
Title: Re: What is it (breather on tappet cover?)
Post by: kiwipom on 30.11. 2018 03:23
pulse Pumps.
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 30.11. 2018 09:23
If you breath in it takes energy (muscle movement), if you breath out it takes energy, if not you die. The piston going down pushes (uses energy) air out of the way. Piston going up creates a vacuum (slows it down, uses energy).  *fight*
In a 650cc twin it's breathing in and out 650cc's of air 6000 times a minute at 6000rpm.
Try doing that yourself without using any energy and not passing out!
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: Swarfcut on 30.11. 2018 09:59
 Musky, as this thread takes on a life of its own, that's all fine an' dandy, but can anyone explain how a small bore pipe open to atmosphere for a nanosecond can achieve any form of crankcase ventilation, with good bores and no piston blow by, let alone on a well worn engine? It would make more sense if the rotating breather bush was slotted to present a larger time period open, rather than just a hole that matches the bore of the breather tract.

  All I know is that by some miracle the system seems to work.  The larger the volume into which the swept engine capacity can be pushed, the lower the crankcase pressure above atmosphere will be, hence linking the crankcase to the primary chaincase on some Triumphs, in an attempt to reduce pumping power loss (or avoid someone else's patent?).

 Swarfy.
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 30.11. 2018 10:30
G'day Swarfy.
I'm no engineer (just a plain old fitter & turner) or physics nut just a feel of the pants rider. All I know is it works. Lap times improved by 5 seconds a lap on a 2 minute lap (that's a lot to a racer).
I can understand your argument (nice not naughty) and yes it baffles me just as how can the suck, compress, bang and blow happen so quickly.  *dunno* (don't have one for WTF) lol.
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: cyclobutch on 30.11. 2018 15:45
So how much of this becomes academic if you switch your parallel twin from a 360 to a 180 crank?
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 30.11. 2018 18:43
G'day cb.
It would still need to breath, but wouldn't need to be timed. There will always be some amount of blow by the rings producing positive pressure. Most multi cylinder car motors have PCV's. My rHonda 1100 has two 1/2" breather tubes exiting the crankcase.
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: kiwipom on 30.11. 2018 20:19
yeah Musky that is obvious so what is the point of the argument ? the engine is going or not going so dont start the bike and save energy, *sleepy* *sleepy*
Title: Re: What is it (breather on tappet cover?)
Post by: duTch on 30.11. 2018 22:05

 
Quote
So how much of this becomes academic if you switch your parallel twin from a 360 to a 180 crank?   

  I guess Beemers be also similar.... maybe
  For what is worth, Gutzzis are similar to that but slightly different with shared crankpin and 90°/270°(ish) firing, and I went through this a bit when I thought I was having breather issues with my Gutzzi which has a LM II type remote breather box of a design much like Sluggo's diagram.,  and concluded with Tom my local Gutzzi guy that the breather box needs to have a volume of half the engine capacity (rule of thumb,  and box is about 100mm x 90mm x 50mm for 846/946cc engine capacity)- I vent it into a juice bottle between the filter pods and that vents out a ' T ' piece towards the pods


Title: Re: What is it (breather on tappet cover?)
Post by: Daithi on 01.12. 2018 02:04
Here is a set-up I ran on my T120. I don't have any data to say if it made any improvement to power or not. The motor did "feel" more powerful and revved out quicker. Wish I access to a dyno back then just to see but there was a definitely a noticeable difference. I miss that bike. Dave
Title: Re: What is it (breather on tappet cover?)
Post by: Rocket Racer on 07.12. 2018 02:38
I'm sure the standard breather arrangement is a fine compromise for average road rally/club run use.
However on a race engine there are so many references to Nortons, BSA's and Triumphs of the period having breathing issues when working hard. Just look at the preunit singles, the XB motors had a breather, which was changed for the ZB motors which was further amended for the goldstars. On top of that articles typically talk about extending the timed breather duration due to the higher road speeds of today.
Add to that 6000-7200 (thats all I'm admitting to) on my road rocket lap after lap is not what the factory had in mind for their over the counter bikes breathing system.
Like Muskrat I run a bunn breather off mine. With the 6 speed box my engine sits continuously in the 5500-6500 range
The breathers allow my engine to not leak but they do deposit a modest amount into the breather catch bottle after a full race weekend.
Title: Re: What is it (breather on tappet cover?)
Post by: berger on 24.12. 2018 01:10
I have just come across a geezer on that face book thing that has been doing some incredible speeds 123mph + on one and 160 on the other[ photos shown of bikes] running A65s on nitrous and turbo's . one of the photos showed a crankcase breather that could have been 1 inch bore. I can't remember his exact words but he said he ended up blocking off the big breather and said BSA must have known that their breather was good enough as the extra one he fitted wasn't needed after all---------- something to ponder on over your mince pies  *beer*
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 24.12. 2018 09:34
G'day berger.
As RR  suggests on a full bore ride it like you stole it the std breather can't do it. My 57A7SS saw 8 grand (in 1st,2nd & 3rd) and 125mph at Eastern Creek with a Bunn (only a std 4 speed). At the end of a race it might have 2oz in the catch bottle.
Even on a road motor it allows the motor to rev more freely not having to suck and blow.
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: berger on 24.12. 2018 15:56
8 grand musky *ex* I have taken mine to 7 in first and second and that sounded scary, I do agree with what you say because mine leaves its mark from the breather when I ride it like I stole it. it was just something that was put on face book and a question was asked about his big breather and he said he blocked it off. no pub for me MAN FLU *sad* *problem* *bash*
Title: Re: What is it (breather on tappet cover?)
Post by: Greybeard on 24.12. 2018 17:48
no pub for me MAN FLU *sad* *problem* *bash*
Oh, that's serious. Have you been to Casualty? I hope you can enjoy tomorrow.
Title: Re: What is it (breather on tappet cover?)
Post by: BSA_54A10 on 24.12. 2018 22:42
G'day berger.
As RR  suggests on a full bore ride it like you stole it the std breather can't do it. My 57A7SS saw 8 grand (in 1st,2nd & 3rd) and 125mph at Eastern Creek with a Bunn (only a std 4 speed). At the end of a race it might have 2oz in the catch bottle.
Even on a road motor it allows the motor to rev more freely not having to suck and blow.
Cheers
It is all in Rex's blog if you can wade through it or the 2 books he has published on motorcycle breathing.
Auckland university is still doing research and no doubt there are a few papers in their archive on breathing should you wish to subscribe .
There is nothing magic about it.
It takes energy to compress a gas and also energy to pull a vacuum.
It takes a lot less energy to pump the air through

Rings do not make a perfect seal so if the rising piston on compression has a vaccuum below it some of the compressed charge will bypass the rings due to the pressure difference.
If the air under the piston is at full atmospheric pressure then there is less pressure difference so less pressure on the charge to bypass the rings.

The same applies on the exhaust stroke.

All the rest is about resonance, everything that applies to exhaust pipes applies to breather pipes.
This is where it gets very complicated because you have to take the stiffness of the tubing & it's diameter into account as well as the length.

The final part is the actual valves used, how much pressure difference is needed to open & close them, at what frequency they resonate , how fast they open & close and how good the seal is.

The last bit is the fluid dynamics of the crankcase gas itself.
Air has a weight thus it has a lag time from the time you start the piston moving down to the time that the air starts to come out of the outlet.
And similarly some air will still be coming out the end of the tube after the piston starts to rise.

The same applies to the air coming into the engine.

For the average rider the performance difference would be hard to notice apart from the fact that the engine no longer leaks.
To the Muskies of the world, it is a very cheap performance enhancer where every little bit counts.
Title: Re: What is it (breather on tappet cover?)
Post by: bsa-bill on 25.12. 2018 10:11
Quote
So how much of this becomes academic if you switch your parallel twin from a 360 to a 180 crank?

If your upto doing that I doubt you'd be stuck with getting it ti breathe properly  *smile*
Title: Re: What is it (breather on tappet cover?)
Post by: Black Sheep on 25.12. 2018 14:45
I know I'm being a bit simplistic, but if you use energy to compress a gas, you regain energy as it expands. So all you need is a timed breather to cope with the excess gas from piston ring blowby and the majority of air in the crankcases is just squeezing and expanding and staying almost but not quite energy neutral.
If you are pumping it continually, might you not be expending more energy?
Title: Re: What is it (breather on tappet cover?)
Post by: Triton Thrasher on 25.12. 2018 15:40
I know I'm being a bit simplistic, but if you use energy to compress a gas, you regain energy as it expands. So all you need is a timed breather to cope with the excess gas from piston ring blowby and the majority of air in the crankcases is just squeezing and expanding and staying almost but not quite energy neutral.
If you are pumping it continually, might you not be expending more energy?

Pressure in the crankcase makes it leak oil.

Rings need combustion chamber pressure to make them seal.  Combustion chamber pressure is the difference between pressure above the piston and pressure below the piston.

Denser air in the crankcase causes more air resistance to the moving parts (windage).
Title: Re: What is it (breather on tappet cover?)
Post by: Black Sheep on 25.12. 2018 20:15
All true but so I suspect are some of my observations.
Title: Re: What is it (breather on tappet cover?)
Post by: BSA_54A10 on 25.12. 2018 21:22
I know I'm being a bit simplistic, but if you use energy to compress a gas, you regain energy as it expands. So all you need is a timed breather to cope with the excess gas from piston ring blowby and the majority of air in the crankcases is just squeezing and expanding and staying almost but not quite energy neutral.
If you are pumping it continually, might you not be expending more energy?

In the mythical engine used by schools to teach the relationship between Pressure , Volume &  Heat you would be almost correct if you ignore the heat radiated out of the engine.
In the real world not quite so.
Unless you are using total seal rings in both grooves you get leakage between the rings & the bore / piston.
So you always get gas bypassing the piston. More on the compression stroke than the other 3 .
Next pumping a fluid requires a lot less energy than compressing one.

But don't believe me .
Go to the blog and see the results form the research engines.
There are other benefits from through breathing but they are a bit on the esoteric side.

The basic problem was the original breathing system was designed to SUCK AIR INTO the engine past all of the oil slingers because they did not use seals on the crankshaft.
This gets overlooked by most people because they do not look back far enough , just at the problem as seen today.
Because BSA's were designed in the  slide rule days the methods were different and usually it was a case of using what they knew from experience worked on the previous models.
When you have a bad case of Beeseritus so play with & learn about everything from the year dot, it becomes apparent.
You see things like bore & stroke ratios that carried on from model to model, because they knew that this ratio worked and would not crack frames or set up sympathetic vibrations that sent the bike sideways at specific revolutions.

In the computer in your pocket days where almost any idiot like me can design an engine then run it without touching a piece of metal, it is difficult to appreciate the problems back in the 40's & 50's when the A7/10 was deigned  and every thing had to be thought out then made in metal to test your idea.

For BSA engine breathing was not a problem they just did what they did with the previous model, till they needed to get better performance from the B44 engine in order to hold on to the only area of motor sport where BSA was still a power thus got the results to promote sales. So the B50 got the closest thing to an adequate breather that BSA ever fitted to an engine.
The B50 engine was pumped up to the highest compression ratio that would stay together, but they needed more Hp and they got that little bit extra by the 1/2" breather.
Ten years latter Yamaha brought out the SR 500 which also used the massive 1/2 " breather to squeeze that bit extra out of the engine.
Had either of them put a timed or controlled inlet on the rocker cover they would have seen another Hp or 2 from that engine .

The easiest way to increase the Hp on an engine was to bump up the compression.
Following that was gas flow within the head so that is where all of the research went.

By the 80's EPA regulations world wide was pushing towards controlling oily gas emissions by forcing the crankcase gasses to be passed through the carb & burned so research on through breathing became a non event.
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 26.12. 2018 08:15
And all this reminds me of an old saying. "You can lead a horse to water but you can't make it drink".
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: wortluck on 26.12. 2018 17:50
When I've been for a 200m ride and park up, I find oil over the bottom of the crankcases and a small puddle at the bottom of one of the centre stand legs.  I check the engine oil and it's the same level - as is the gearbox and primary.  The bike runs fine and doesn't seize up after a 'spirited' ride.  If the oil is down to the breather, surely it's doing its job and we shouldn't be worrying too much about it.  Also reassures me about why the oil is there.  Shoot me down if I'm missing something. *conf* *conf2* *doubt*
Title: Re: What is it (breather on tappet cover?)
Post by: BSA_54A10 on 26.12. 2018 22:12
When I've been for a 200m ride and park up, I find oil over the bottom of the crankcases and a small puddle at the bottom of one of the centre stand legs.  I check the engine oil and it's the same level - as is the gearbox and primary.  The bike runs fine and doesn't seize up after a 'spirited' ride.  If the oil is down to the breather, surely it's doing its job and we shouldn't be worrying too much about it.  Also reassures me about why the oil is there.  Shoot me down if I'm missing something. *conf* *conf2* *doubt*

If you have been flowing the thread, you will note that the breather as fitted was described as adequate for low speeds and getting progressivly worse as engine speed rises.
If you had fitted a through breathing system, your cankcases would be clean & dry.
This is why most people fitted them, not for the performance improvement that few if any would notice or even need but to cure the "marking it's place" oil puddles left on friends drivewys.
I just park on the road or the grass verge.
Title: Re: What is it (breather on tappet cover?)
Post by: berger on 27.12. 2018 01:28
AHAH now then musky 02-05-2014 horses for courses *smile*. the thing I will be needing to know is where I can get the said bunn breather or similar  from for my hopefully going to be a nutter engine for the featherybed project ,or how to improve the breathing if said bunn is extinct *eek* come on fess up who's hoarding the buns *fight*
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 27.12. 2018 04:32
G'day berger.
Lost me on the date so I went back through my posts. Post # 3703 was that date and a link to my clubs show and a pic of my Cafe. Yes she needs to breathe.
Unfortunately the Bunn is no more. A mate was experimenting with a few bits & pieces. He found these work quite well, about 2/3 way down the page. Need 1 for in and 1 for out. http://www.hollandnortonworks.eu/en/exclusive-commando-parts
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: BSA_54A10 on 27.12. 2018 05:35
G'day berger.
Lost me on the date so I went back through my posts. Post # 3703 was that date and a link to my clubs show and a pic of my Cafe. Yes she needs to breathe.
Unfortunately the Bunn is no more. A mate was experimenting with a few bits & pieces. He found these work quite well, about 2/3 way down the page. Need 1 for in and 1 for out. http://www.hollandnortonworks.eu/en/exclusive-commando-parts
Cheers

Rex was doing them again, to order.
Email him
Title: Re: What is it (breather on tappet cover?)
Post by: Sluggo on 27.12. 2018 08:39
Unfortunately the Bunn is no more. A mate was experimenting with a few bits & pieces. He found these work quite well, about 2/3 way down the page. Need 1 for in and 1 for out. http://www.hollandnortonworks.eu/en/exclusive-commando-parts
Cheers

Quite right,, There is many MANY long arguments about the Bunn breathers, Seems tiring, However they did work to a degree.  But my take away whether the previous solution the infamous Motomite breather, The bunn or the other versions is no need to fixate on a "Specialty" fitting with accompanying markup.

I am all for supporting vendors, But dont get so wrapped up stepping over a penny to spend a dime.  There is a variety of breathers that work quite well and motorsports compatible without buying a Binford 1000 model.   The unit that came stock on later model HD sportsters and Buells works quite well, and used on a variety of cars and motorcycles if you cross reference the part number.  The metal one on the link Musky provided is a common variety as well and IIRC is specced for lawn mowers and Yamaha ATVs??? 

The issue was the original moto mite was a plastic unit and tended to fail from heat and oil eventually, The Bunn was better, But there is a wide variety of other units and very inexpensive. Dont know about other countries. But here in the US many autoparts stores like NAPA will let you look thru their supplier catalogs and You can find one to suit for a very common application so, No need to order a specialist part.

Norton people seem to be the most prone to that issue.  I have repeated the story many times, But the original Norton 850 starter "Assist" was a reject prestolite starter for HD sportsters but did not live up to its demands. So sold to Norton as "Good enough for a limey bike".

The solution to the anemic starter was conversion to 4 brush system and better cables and connections and battery..  Now this is well documented in HD circles and the parts are not too expensive. But Norton people seem adverse to hearing this, So they stick their fingers in their ears and say loudly "Nananana nah,,,,cant HEAR you"...  And instead pay 2-3x as much for the same bit of kit from a Norton vendor.

History repeats, The transmission on  a Norton 961 is a HD Sportster/buell 5 speed, A suzuki clutch and alternator. The starter comes on a wide variety of Harley, Buell and even John Deere, Kubota-Yanmar, and other 3 cyl diesel tractors.  You can literally buy parts for them at the local lawn & garden store.  Norton people insert their fingers in their ears, and same "nanananana nah"  I know people whos Norton 961 spent all of the summer in dealer service waiting for parts from Blighty.  A local had this problem as well and happened literally in sight of a Lawn & Garden store where I could have walked to it and sourced the parts to repair his bike with nothing more than a screw driver.  He refused, called a tow truck and few days later took the bike to Seattle to the nearest dealer 3hrs away where it sat for 4 months.

The solutions can often be close at hand and very inexpensive, Not that CNW and other shops dont appreciate your money $$$$$$$$  *thanks* But its likely NOT a zebra when you hear hoof beats in central park.
Title: Re: What is it (breather on tappet cover?)
Post by: wortluck on 27.12. 2018 08:50
Cheers Trevor - only skimmed through this thread.  My main interest was how normal the 'puddle' was (only small) and whether it was having an effect on oil levels (which it isn't). *smile*
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 27.12. 2018 09:21
G'day wortluck.
It doesn't take much oil to make a mess. At least not enough to show in the tang/box or primary. If you had a real accurate dip stick you might see a few ounces in the tank but that would be a BIG mess.
Two duck bills would do for road riders.
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: wortluck on 27.12. 2018 09:30
Cheers Musky - wot d'you mean by 'Two duck bills would do for road riders'?  Also, 'tang/box? - presumably gear box.  Just trying to get my head round the lingo. ;)
Title: Re: What is it (breather on tappet cover?)
Post by: Sluggo on 27.12. 2018 09:39
Oops, You know what they say about a Yamaha XS650 right?  Yamaha copied a BSA and made it better???   *eek* ::hh:: *countdown*

So, Yamaha guys argue about the same topic... 5 pages,
See: http://www.xs650.com/threads/crankcase-breather.1771/page-2

So this is the common breather, MikesXS supplies them for $23
See: https://www.mikesxs.net/yamaha-xs650-reed-type-engine-breather-valve-pcv.html

But alternatives: " Yamaha YZF R 125 EGR exhaust valve, it has the pipes at 180 so it fits in a straight pipe run. (found on ebay for less than 5 pounds)

Fram PCV valve, $5.00 
See: https://www.amazon.com/FV380-Positive-Crankcase-Ventilation-Valve/dp/B000C33LK6/ref=sr_1_149?ie=UTF8&qid=1545902914&sr=8-149&keywords=PCV+crankcase+breather
Fram metal body $4.95
See: https://www.amazon.com/FV299-Positive-Crankcase-Ventilation-Valve/dp/B000C2ZJNY/ref=sr_1_152?ie=UTF8&qid=1545902995&sr=8-152&keywords=PCV+crankcase+breather
AC Delco (I use these a lot!)  $8
See: https://www.amazon.com/dp/B000C9QVD4/ref=sxbs_sxwds-stvpv2_3?pf_rd_p=6375e697-f226-4dbd-a63a-5ec697811ee1&pd_rd_wg=6qDUE&pf_rd_r=J5F9R07G20ZH38K0MTC1&pd_rd_i=B000C9QVD4&pd_rd_w=p0h76&pd_rd_r=00ffdecb-c82b-49a3-b929-bf1a16067802&ie=UTF8&qid=1545902995&sr=3
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 27.12. 2018 10:24
G'day wortluck.
Duck bills are just a rubber hose flattened at the end. Blows out but can't suck in. Used on lots of bikes to drain airbox.
G'day Sluggo.
Yes many ways to get over the problem but tried and tested (Nortrun owners are finicky) on a mates SR/XT/TT500
Works well. Going to put them on my 76 XT500.
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: BSA_54A10 on 27.12. 2018 12:18
Quote
I am all for supporting vendors, But dont get so wrapped up stepping over a penny to spend a dime.  There is a variety of breathers that work quite well and motorsports compatible without buying a Binford 1000 model.   The unit that came stock on later model HD sportsters and Buells works quite well, and used on a variety of cars and motorcycles if you cross reference the part number.  The metal one on the link Musky provided is a common variety as well and IIRC is specced for lawn mowers and Yamaha ATVs???

Rex was commisioned to fix a HD breathing problem.
Not sure if their breathers  are part of his work or not but he was getting royalties from quite a few companies.

As for auto PCV valves, brake check valves, duck bill valves, even BSA's own preunit flapper valve, they all work to some extent and some better than others.
But none of them work all the way from idle to valve bounce.

Just like end fed cranks, you don't have to do it & for most BSA owners the side feed through the main bearing will be good enough.
So weather you need one or not will depend upon your particular bike, your riding style and your ego.
If some oil leaking out the rocker box covers and a lot more from the various orrifices does not bother you, and it does not bother me then the bike will be fine just as it is.
After all it is your bike & you are entitled to fit or not fit whatever you please.
However they do work and they work much much better than anything else on the market.
The research, facts & figures are all there and if you can't be bothered to go through the 500 pages of blog, then you can buy the book.
The early one has all of the details & research results & to be quite frank is a difficult read
The second was a distilled version of the first with the information most 1/2 competient owners would need to fabricate their own.
The only thing he did not give away was the brand of the only material tested that did not suffer from resonance.
The M20 for instance is fairly well oil tight to about 4000 rpm.
After that it covers everything behind it with oil.
But peak torque is around 3600 so there is little use in valve bouncing it.

There are a lot of things that can affect both breathing & the amount of oil that is expelled.
A customer had course to run his new Triumph at & over redline for extended periods.
When it was safe to continue on, he got about 5 miles before the engine locked up solid
Why ?
Because ring flutter had pumped the entire contents of the sump out the exhaust pipes.
Indeed as we were pushing it up into the van, oil poured out of the muffler.
We thought it must be a cracked head, but the head was fine, the gaskets intact but the head was coked worse than a WWII tractor running on kero.

BSA knew the flapper valve did not work particularly well which is why the Gold Stars got the timed breather off the magneto drive and eventually the tacho drive as well
However right up till the B31/33 series got replaced by the C15/B40 the flapper valve remained on the road versions.
Title: Re: What is it (breather on tappet cover?)
Post by: berger on 27.12. 2018 13:08
musky I was referring to your---you can lead a horse to water but can't make it drink bit, which you mentioned in the previous breather post of that year. I thought you might have remembered and put it in again on purpose . Well chaps thanks for the information and links -stored for easy finding again--- it gives me a lot to think about and when the time comes the engine will be getting a breather mod and some sort of rubber mounted head steady, something else to keep me awake at night
Title: Re: What is it (breather on tappet cover?)
Post by: Triton Thrasher on 27.12. 2018 16:12

Two duck bills would do for road riders.
Cheers

Why stop at two!

(https://www.a7a10.net/forum/proxy.php?request=http%3A%2F%2Ffarm5.static.flickr.com%2F4021%2F4414080054_09ae990ac9.jpg&hash=bc35391e716df84a8586e05d4ee7abda)
Title: Re: What is it (breather on tappet cover?)
Post by: wortluck on 27.12. 2018 16:48
Er, where do you put the duck bills?  No, GB, not there *eek*
Title: Re: What is it (breather on tappet cover?)
Post by: chaterlea25 on 27.12. 2018 23:44
Hi Berger,
Quote
and some sort of rubber mounted head steady

This post shows how I made a rubber bushed  head steady

https://www.a7a10.net/forum/index.php?topic=2912.0

Where have the years gone *eek*
I made the first one somewhere around 2000-2002,

John
Title: Re: What is it (breather on tappet cover?)
Post by: berger on 28.12. 2018 01:26
I like it john comes up trumps again *contract* no patent yet is there?, so that is the way to go and I can go to bed thinking about all the other 99,999 things to do *roll*
Title: Re: What is it (breather on tappet cover?)
Post by: wortluck on 28.12. 2018 10:32
When I managed to shear off the 'tab' on the front lower mudguard stay, I found an old bracket from the shed, wrapped some old inner tube round the inside, and belted it all up - do I qualify for a cookie?? Ref: #bodge-up No.46 (apologies again to the purists).  I have now got a spare stay for when I wreck it again. *eek*
Title: Re: What is it (breather on tappet cover?)
Post by: berger on 28.12. 2018 16:25
I have not been to the pub AGAIN 7 days *dribble* *eek*,just one question as regards the rubber bush mounting to you wise and enlightened people *respect*, as it will be fixed in the featherybed would it be any advantage to mount the brackets holding the bush directly above the engine ie vertical, or to one side as the bsa frame mount is located.
Title: Re: What is it (breather on tappet cover?)
Post by: muskrat on 28.12. 2018 19:11
G'day berger.
Getting a bit off topic but fore and/or aft, not vertical.
Cheers
Title: Re: What is it (breather on tappet cover?)
Post by: wortluck on 28.12. 2018 19:53
I managed one day Berger ol' son.  Best get down there and reassure the publican you're still with us. *smile*