Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board A65 Crank case breather vent location ?

Im not talking about the chain oiler which is fed off the primary case BUT the vent in the crank case ...

Obviously it must be close to the end of the cam with the timed breather on it but where?

a description would be helpful but even more so would be a pic of it if anyone has one

Thanks Guys

Tucked away above the front drive sprocket

I assume your question is to find the location?

cool thanks DMadigan

no wonder i couldn't see it .......up above the alternator wires ......

i have a spare set of cases but you know how it goes right at the back behind a load of stuff ...my theory when packing my bits away was "put the least likely to be needs bits in the hardest place to reach"

well it was a good theory at least

Cheers

Just a thought, does anyone know why BSA DIDN'T cast a spigot in place like Triumph?

They didn't want us to know when there was blow-by? Just another way to ensure the chain got well oiled?

I now know when I've got blow-by, blown head gasket, or other issues:



Tom

Nice, I like your design

I don’t... a lot of oil comes out of that breather.

As the oil vapours leave the crankcase they will cool rapidly and condense at the elbow. That condensed oil won’t travel properly north up the hose and less so as it fills with oil it will be less efficient at breathing than it would dry.

If you can keep it so it isn’t climbing so high it shouldn’t be an issue. Better still going into a catch tank.

You’d be better blocking it off and making a vent at the rocker box or via the timing side.... or turn the engine triumph style and have it share the Engine oil with the primary.

And also, when that excess teflon tape comes off in there...

You mean like most of the BSA racers I've seen?
Maybe they liked marking their territory with the small oil spot on the pavement under the primary?
Maybe cause they all went to Umberslade and took a long nap until someone woke them up to tell them the company was out of business.

So now I guess the teaspoonful of oil that is deposited on the garage floor, after a spirited ride, is probably blow by.
At least the chain is getting oil!
SteveG

It could be blow-by.
It could be gear oil.
It could be primary leakage.
It could be head gasket.
It could be leakage from case joints.

That is the question.

The definition of "oil tight" was a bit different back in the day...
Personally I like NOT to fit a breather hose on a Triumph, letting it breathe freely as on an A65. A hose will eventually get plugged with snotty oil and vapor emulsion and render the breathing system useless. A spot of oil under the engine keeps the modern bike wisecrackers happy!
Letting it breathe through the primary case is perhaps a low tech solution, but it works well even when your engine develops blow by.

SR

We drop a bit of Cola under a mates GT750 Suzuki at meets then stand back and watch him investigate for an hour or so

The only time I've had oil come out the timed breather on either of my A65s was when they were wet-sumped. I can't say I've ever had a lot of blow-by, but I would think it would be pretty hard to blow oil out that breather due to its location, up high and behind the camshaft.

A small puddle under the chainway after riding is more likely due to a worn tranny oil seal or clutch "back door" oil seal. You may be able to determine the source of the oil by its smell or color - gear oil has a very sulphury smell. If you run ATF in your primary, you can identify it by its reddish color.

But I'll go with the consensus that a little oil here and there is not necessarily a bad thing - for one thing, it's a good rust inhibitor.

OK im a bit surprised that my inquiry re location drew so many comments ( a good thing)

The reason i originally asked was that 2 weeks or so back my A65 decided it would demonstrate its displeasure about not getting any robust use. .. I stopped to get gas and there was A LOT of oil under it ....a lot DANG! ....wasnt far from, home so i got back and had to add something like 1 liter to the tank . It seemed to be mainly on the drive side.

Any way after much head scratching about likely causes i concluded that the scavenge ball had some how got stuck down an wasnt picking up ( a bit of sticky *rap dislodged by getting it going robustly i guess)

Anyway topped the lost oil up ....ridden it twice since then and its fine....just one of those things....it is normally pretty arid

AND NO it had not wet stumped whilst sitting (no smoke on start up) it hadnt stat that long anyway

IT is NOT blow by or it would not have self resolved

IT is not oil pump as pressure and return are fine now (i have a gauge fitted)

I refilled it to the EXACT mark on the dip stick and it has stayed there

dead issue now but it sure got me thinking

Ig, I'm still going with the wetsumped theory, notwithstanding the fact that it didn't smoke: 1. It was sitting, albeit not that long. 2. You had to add oil to the tank.

So, once a week then?

Mine drips out of the breather following a good threshing. Not a drop if I’ve been riding like “driving miss daisy”

If it aint leaking oil, you aint riding it hard enough.

When it leaks as much as a triumph, do something about it.

I'd be concerned if a little didn't come out of the crankcase breather!

I added oil to the tank AFTER it chucked it out which was approximately 20 miles after i started it ........it hadnt wet sumped smoke on start up is the big indicator

It lost around a liter not "a few drops" (as others have commented ) going by dipstick level ......the oil was not even showing on the dip stick but there was still enough in the tank to get me home .......teh strange part was how i noticed when i stopped for gas around 2 miles from home but when i got home the issue was over ie no bucket loads on a fresh peice of paper

Well its either burning it or throwing it out somewhere, oil doesn't magically vanish.

[quote=koan58]Well its either burning it or throwing it out somewhere, oil doesn't magically vanish.[/qu

i have explained at length that it was an isolated event which self resolved

Ok, it's apparent that the oil went from the tank, into the crankcase, and out the breather. Whether it did that before or during your ride, that still spells wetsumping in my book.

It's more typical of BSAs to wetsump while sitting, but perhaps, as you surmised, the scavenge pipe was temporarily blocked or something like that.

When my A65 was wetsumping (before I replaced the oil pump with a cast iron model), it sometimes did not smoke on startup. OTOH, it usually spewed the oil out the breather immediately upon startup. I think it may depend on what position the pistons were in when it was put up. One time, after sitting all winter, it blew oil out the head gasket upon starting (actually just kicking). I surmised that the pistons were left in the down position, and the cylinders filled with oil. Oil does not compress, so it had to go somewhere.