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Elephants trunk

Chrish

Well Known and Active Forum Website User
VOC Member
G'Day,

I am fitting an elephants trunk breather to the twin, in lieu of the timed breather, I know it looks like an add on, but I'm going with it. My questions are; is there a preferred placement of the one way valve in the hose i.e. nearer to the ET136/1 or at the furthest end and should there be a oil mist trap somewhere in the horizontal of the hose under the petrol tank.

Thanks in advance......

Chris
 

davidd

Well Known and Active Forum Website User
VOC Member
Chris,

I hope you get a reply from someone that uses one. I use the Ducati one-way breather. I would place the check valve at the end of the vertical run so oil mist that condenses on the vertical portion of the hose can drain back. Any oil that gets by the valve will not drain back and will exit.

David
 

Chrish

Well Known and Active Forum Website User
VOC Member
Thanks David, the Ducati one-way breather, is that on your replica race bike or a twin? if on the twin how is it set up?

Chris
 

b'knighted

Well Known and Active Forum Website User
VOC Member
My Knight was fitted with a breather by the Mac Read. He no longer makes them.

They were abused with the name of elephants trunks by the many attempted imitators, most of whom totally misunderstood the principles Mac used.
Mine has a specially cast ATD cover with a vertical bore into which is inserted (sealed) a vertical valve. I have never seen inside but believe it has a nylon ball which is blown upwards by crankcase pressure then drops to seal the end of the tube. This is enclosed in a sealed body which vents vertically into a rubber hose (hillman hunter heater hose)(alliteration helps to remember) this passes into a baffled box between the series D crash bars. Any oil knocked out of the air or condensed is sucked into a capilliary tube to the D breather cap when the pistons rise. My system then vents through the left crash bar. While it is possible to feel the engine breathing through this the exhaust is clean air. The oil consumption is negligible.

Mac's version for non faired bikes had a baffle chamber directly bolted to a D cap over the front exhaust valve. Someone else (I was told who by "plasticbeer" but instantly forgot) made some very attractive all stainless versions. These may still be available.
My Shadow has a system made by Phil Primmer which has a pipe from a non gauzed ATD cover, possibly from Kemps, through a large bore pipe to a reed valve. I think this relies on the length of pipe below the valve to let any relaesed oil vapour condense and drop back into the timing chest. I think Phil's intention was to fit a one way inlet valve with a Bunn filter, on the rear inlet valve cap, to reduce vacuum in the crankcase.

Cheers,
 

Black Flash

Well Known and Active Forum Website User
VOC Member
My brother used the system described by Ian but with the stainless pipe. I liked the looks much more than those with the rubber hose.
The drawback was the stainless pipe somehow amplifying the sound of the plastic ball going up and down.
It certainly added a new timbre to the percussion band playing in the timing chest. well at least at tickover, higher up the rev range the the ususal clatter took the lead.
good news was that the engine was oiltight and dry like a desert.

something else, I just received a phonecall from a friend who fitted the Neal Videan gasket sets to his cylinder heads oilfeeds / gallery. after two years of fiddling these gaskets stopped all leaks from the top instantly. he really praises those items and is actually over the moon with the result.
According to him the very best value for money upgrade you can get.

Bernd
 
Last edited:

Chrish

Well Known and Active Forum Website User
VOC Member

Thanks Bernd,

I am going to use stainless braided covered hose, the reason I am trying this is i have a small leak from the front pushrod tube and I'm not taking the head off just for that......... :)
 

vibrac

Well Known and Active Forum Website User
VOC Member
why anyone needs this sort of thing beats me
I fitted a generic PCV valves from an american car shop 1-1/2 inches long and 3/4 inches diameter just pushes in to hose on the front engine cap D style you cannot see them unless you squat and stare. They cost a couple of quid many variations the one I have is Standard Motor Products V213 PCV Valve but have a rummage in any classic car shop and you will find similar just a metal tube with a ball valve
On the 1275cc Racer I had one on the inlet rear valve cap hose and one on the front hose about 2" from cap at highest point (largish bore hose for the run) to a catch tank as per regs-500cc the whole season -2 table spoons of oil in the can. as I run on Castrol R I poped it back in the tank :)
 

Peter Holmes

Well Known and Active Forum Website User
VOC Member
My Knight was fitted with a breather by the Mac Read. He no longer makes them.

They were abused with the name of elephants trunks by the many attempted imitators, most of whom totally misunderstood the principles Mac used.
Mine has a specially cast ATD cover with a vertical bore into which is inserted (sealed) a vertical valve. I have never seen inside but believe it has a nylon ball which is blown upwards by crankcase pressure then drops to seal the end of the tube. This is enclosed in a sealed body which vents vertically into a rubber hose (hillman hunter heater hose)(alliteration helps to remember) this passes into a baffled box between the series D crash bars. Any oil knocked out of the air or condensed is sucked into a capilliary tube to the D breather cap when the pistons rise. My system then vents through the left crash bar. While it is possible to feel the engine breathing through this the exhaust is clean air. The oil consumption is negligible.

Mac's version for non faired bikes had a baffle chamber directly bolted to a D cap over the front exhaust valve. Someone else (I was told who by "plasticbeer" but instantly forgot) made some very attractive all stainless versions. These may still be available.
My Shadow has a system made by Phil Primmer which has a pipe from a non gauzed ATD cover, possibly from Kemps, through a large bore pipe to a reed valve. I think this relies on the length of pipe below the valve to let any relaesed oil vapour condense and drop back into the timing chest. I think Phil's intention was to fit a one way inlet valve with a Bunn filter, on the rear inlet valve cap, to reduce vacuum in the crankcase.

Cheers,
I think it was Ivan Caffrey, I have one of his beautifully made breathers but I am not entirely sure that the concept actually works as a valve, it certainly works as a breather but it also creates alarming amounts of mayonnaise, I think because the thin wall stainless steel pipe is stuck out in the cold air flow, in any event I think that the nylon ball cannot hope to flutter up and down at the required speeds to act as a true valve, for sure you can here it on tickover, it adds a rythmical percussion samba beat to the general cacophony of sound, for me it got a bit too much and I removed it. I think if you want a breather a reed valve must be the way to go as the reed will be doing exactly what it was designed to do, react open and close to very fast pulse pressure changes. I am not an engineer and may be ridiculed by some of the very clever people that belong to the club.
 

bmetcalf

Well Known and Active Forum Website User
VOC Member
Steve Hamel's Bonneville bike has a Ducati reed valve breather. He modified a D breather cap and a Duc breather for me, but it seemed to pump oil while at one of the adjuster positions. I had added some mesh inside, but never really developed it to be a perfect solution after I timed my timed breather correctly. Obviously, they certainly work on Duc's. The good thing is that they are cheap to buy at Duc shops because the customers love to replace them with aftermarket billet units and the shop has the used ones gathering dust.
 

john998

Well Known and Active Forum Website User
VOC Member
Hello, It was indeed Ivan Caffrey who made the stainless version, mine does indeed add to the timing chest symphony but reduces the oil consumption by a goodly amount. Sadly he no longer makes them.
No problem with mayonnaise though, indeed only air appears at the outlet. If I need reassurance that all is well in the timing chest I plug the outlet with my thumb momentary and that rumble disappears. John.
 
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