Still confused about breathing

[iansoady]

Well, I've stripped off all the primary drive and cases to look closely at the breathing arrangement on my 1961 (1960 engine) Flash. And all there is is a downward-pointing hole under the left hand end of the camshaft tunnel. I'm assuming this is why there are always a few drops under there when I stop. I hate bikes that drop oil.....

The parts list (Draganfly) shows a breather pipe part 67-922 for all A series 1950-62 but the drawing (which is very indistinct) seems to show just a straight pipe exiting backwards. Clearly wrong as that would just point straight down but is depicted as horizontal. Interestingly, the photos in the Haynes book of lies also don't show any breather pipe.

I've asked C&D about it and they don't have any breather pipes in stock (and have never been asked for any....) So I'm proposing to glue an elbow into the hole with JB weld or similar and run a flexible pipe back to the chain (or even to the back of the bike).

Sound reasonable?

[brackenfel]

Hi Ian,
There was a on something like this in the past but I can't remember what it was called at present!! (i must get better at navigaation on the Forum!). I couldn't find anything "official" by way of a breather pipe either, helpful souls here on the Forum suggested this might be a fairly common "owner mod".. Still not sure!

At the time I posted this pic :-

Is this the position you are referring to? Mine has this brass pipe which was surrounded by Hematite. I'll simply replace that with Hylomar - I've bought a small length of plastic pipe so I can decide where any oil ends up!!

Hope this is of help..

Adrian

[iansoady]

Yep, that's where the hole on mine is. The pic I've attached allegedly shows the breather pipe together with a clip (67-923), which clearly would be redundant given the size of the pipe you have.

[iansoady]

Having now poked about a bit more I can see that the hole actually goes at around 45 degrees - and I can push a 3" bolt all the way in, so next step is to make up a pipe with a 45 degree bend in it.

[A10Boy]

The hole is a drilling which goes all the way across the top of the camshaft trough to the timed breather. If your bike has an oiling problem, wet sumping or something, it will blow oil from here. Most engines will drip a little, but anymore indicates a bigger problem. I thought only plunger engines had a pipe fitted.

[iansoady]

I think mine is doing what you call "dripping a little" - but I've managed to get my previous bikes oil-tight (except for the notorious primary chaincase on the Velo) and I refuse to admit defeat on this one.....

[A10Boy]

It could be primary chaincase or gearbox oil. Obviously engine oil will look dirty. chaincase oil will be clean. I use red ATF in my chaincases easy to see then.

[BSA_54A10]

It was designed to drip oil from there.
Some earlier bikes had a longer copper tube that was clamped to the back of the primary and exited onto the rear chain.
Breathers vent the crankcase fume.
It is called fume because that is exactly what it is, air mixed with finely atomised oil.
These very fine oil particles will condense into oil drops.
If you can not live with the bike working as BSA designed it then either buy & fit a 5 stage oil seperator on the breather tube. or fit a phelum chamber onto the carb big enough to dissapate the pressure pulses from the breather and run the vent there like an automotive PCV system.
Or go buy a modern "retro" styled Honda

[iansoady]

Or go buy a modern "retro" styled Honda

No need to be offensive. As a qualified engineer and rider of British "classic" bikes for over 40 years I am well aware that there are a number of design compromises in most of these which can be addressed without altering the basic concept. I do not intend to reinforce the perception that all British bikes leak oil - most do so because of the hamfisted attempts at "maintenance" by impecunious and incompetent owners over the years.

I'm sure that Bert Hopwood would not have "designed" any machine he was associated with to drip oil, hence the extension you refer to and which I intend to emulate.

BTW it's plenum not phelum. No idea what the latter is.

[RichardL]

Or go buy a modern "retro" styled Honda

Okay, okay. I think Trevor was just being tongue-in-cheek humorous with this comment about the Honda (one could do worse). I will slightly disagree with Trevor about the reason for the breather (without setting myself up as some ultimate expert). I don't beleive it was "designed" to drip oil, but was, indeed "designed" to vent the crankcase which contains mistified oil (as opposed to our forum of mystified oilers). By my reckoning, for my '55 swingarm, the venting occurs 90 deg ATDC, which should represent close to neutral crankcase pressure. Also by my reckoning, the only reason for the breather is to keep the crankcase near one atmosphere, so that oil can be pumped in and out with respect to the one atmosphere sitting on top of the oil in the tank.

With regard to the "tradition" of drippy British bikes, great admiration for your success in the area of driplessness. However, while I might be less fastidious or peccadillocious about solving the dripping riddle, I light-heartedly take exception to ascribing my drips to being "hamfisted," "impecunious" or "incompetent. As for Bert Hopwood, I think the existence of the tube says that BSA expected some drips but they wanted them on the shed floor instead of the bike.

Richard L.   

[iansoady]

 

[BSA_54A10]

No I was not trying to be offensive, just make a point.
They were never designed to be totally oil tight.
The breather drips oil onto the rear chain that is why it is in that impossible to get at place.
The clutch leaks oil, slingers work sort of but they are not oil tight nor were they ever meant to be. As dose the gear change.
In the "period" which I am sure you will remember there were felts fitted to absorb the oil all over the place and dealers replaced these whenever the bike was serviced.
Now that your friendly BSA dealer has gone the way of the Dodo we do our own servicing and never fit the felts so it drips.
Drips of oil were considered to be OK till well into the 80's. Even Rolls Royce was happy for oil to drip from the cranks of their 6.7 liter V8's till the twin turbo Bentley Continental which I think was about 1984 when they finally fitted oil seals front and back.
However I do take your point that a lot of bikes do leak more than they should due to parts worn well past the end of their service life.
FWIW I did 10 years of an engineering / science and have ridden beesas all of my life as my regular daily transport till the early 90's.
I rode my A65 and occasionally the B40 as back up bike for work and did over 100,000 miles a year for nearly 20 years.

Now, it is your bike and if you want to engineer it above & beyond as new condition then you are perfectly entitled to do so, as are all of the owners who paint their bikes in 2 pack, chrome over painted parts or whatever makes them happy and do so with my best wishes.

[iansoady]

Point made Trevor, sorry if my reply was a bit chippy....

The oil mist from my breather just seems to end up all over the frame tube just below it. It does seem rather odd that the plunger bikes, where the gearbox sprocket would be closer to the breather, had the pipe whereas it was deleted on the s/a machines.

I attach a picture of what I have so far, made of a bit of recycled 8mm central heating pipe.

[trevinoz]

Ian,
         With that piece of tube fitted you will have difficulty fitting the inner chain case, assuming that the steel section is fitted.
Probably best to point the tube to the ground as any oil squirted onto the chain is going to the ground anyway. Or all over the rear wheel and other bits.
Trev.

[iansoady]

Hi Trev,

I've offered up the primary chaincase - and the reason for the odd bend in the pipe is to clear the lower edge of the projection on the back that covers the front sprocket. It may need to go a bit lower yet.

Mine doesn't have the pressed steel bit covering the chain below the toolbox but I may rig something up - as well as a support for the pipe to stop it flapping about.

The other thing I was a bit concerned about was the chain whipping and catching the pipe, although as it's soft copper it shouldn't do too much harm.

I may slip some flexible pipe over the end of the copper and take it to the back of the bike - we'll see how it goes.