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Et159

derek

Well Known and Active Website User
VOC Member
I connect a plastic tube to the breather outlet and blow down it, turning the engine at the same time you can definately tell when the valve shuts and opens. If you have a degree plat fitted it is a very easey matter to set the valve correctly. Remember that the spindle may not be in the correct position, so that this method works regardless.
 

GBewley

Well Known and Active Website User
VOC Member
Of course, Derek is correct in final timing of the breather. Setting it up as I stated, which is the documented method, will get you very close, however. A good thing to do, should you have the breather spindle out already, is to ease the material around it at it's slot so that the air can more easily flow out. This recommended by PEI, along with other improvements, in "Tuning for Speed," I believe. Elsewhere if not there.
 

Tom Gaynor

Well Known and Active Website User
VOC Member
Related question:
As fitted at the factory, the breather tube, A51S leads downwards via a banjo, to a tube A52/2AS, and through a hole in the RH front engine plate, where, on M018 it appears to stop an inch later. The whole thing can't be much more than a foot long. Here's the question: is that true? The factory-fitted breather stopped just behind the front engine plate?
Because if it were made long enough (as suggested in KTB for instance) to reach the back of the bicycle, then the resistance to flow would be MUCH greater. If it were now a four foot run, the resistance would be four times greater. The result might be a breather that was largely ineffective, even when the slot was opened out to the max. Like mine was.
The underlying puzzle I'm trying to solve is: why are breather improvements such a talking point? Is it because owners have disabled the design by extending the pipe? Because if that IS true (Lindie...) it would explain why so many motors seem to take an easier route and breathe through the dynamo.
But there must have been a time when breathers worked. It was after all Phil Irving who designed the motor, and PEI was no fool. Anyone adept with a Ouija board would do us all a great service by asking him...
Opening up the tube ID would counterbalance increased length, so civilisation might in fact, yet be saved. My 1960-ish (WVA793, where are you now?) Ducati 175 had an open (untimed) breather about 2 foot long, that was 5/8" ID, roughly 3 x the cross-sectional area of the Vincent breather. Did Ducati know something?
(Such calculations are an essential part of the engineering for drilling oil wells: make the pipe long enough, and small enough bore, and drilling fluid will never reach the bit, fa less flush the cuttings back to surface. So there is a bit of elementary science behind this.)
 

GBewley

Well Known and Active Website User
VOC Member
Tom,

That is indeed the way the bikes were originally set up. And I agree with your thoughts that longer hoses make for more resistance.

I think the fact is that the original setup tended to oil the machine and so a lot of folk, some years on, and deciding it (the bikes available) wasn't going to get better, so let's improve the one we have, started playing with ways of eliminating the perceived problem. PEI gave us the answer in the upward hose and enlarging the slot in the timing sleeve. Still, I contend that the combination of a very small outlet and the blowby that many of our bikes' rings allow easily overcomes the design. Fresh top ends don't have as much problem.

I originally made an extension which ended before the rear axle. On this, Mr. Stevens should have been followed as before the axle will lead to oiling the rear end whereas behind the axle leads to clean running. If they are out or new ones are required, I open up the bore of the breather spindle a bit. Doesn't take much to increase it's volume a great bit, and as it is not terribly stresses (no springs bearing, etc.) I feel safe in doing so. I also open the area of hte case around the breather spindle slot. Still, you are limited by the bore leading to the breather banjo or the part made to allow the hose to go north over the cylinders.

Bottom line is that I believe the original system was marginal. As my currently on the road twin is an 1147 or so, it has even more trouble. I tend to just let it be a bit dirty. As the cliche goes...at least it isn't rusting...
 

Tom Gaynor

Well Known and Active Website User
VOC Member
As a colleague, the inventor of a particularly neat way of doing something remarked, "It isn't successful because I have a track record of success in designing these. It's because I have a long track record in failing. I know at least 18 ways to design one that doesn't work."
Which would put him about 10 failures ahead of me if we were talking Vincent breathers. I think the one that works is my eighth.

Have a Guid New Year, everyone.

Tom
 

ernie

Well Known and Active Website User
VOC Member
As Glenn sez, the standard breather is at best marginal. There have been many modifications and additions, I can think of 5. Here is mine. Comments?

No oil is ejected.

By the way Tom, have you had a foot of snow up there?

Ernie
 

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Tom Gaynor

Well Known and Active Website User
VOC Member
A mere six inches, Ernie, in one night ('twas the night before Christmas, by chance) then zilch. Baltic cold though, even for we hardy northern chiels. Note that said hardy northern etc regard Yorkshire as the deep south, and everything south of that as positively equatorial.
Quite impressed therefore that you should take a Ducati to Elstree at -2. Poor bugger must have been frozen, and pining for Bologna.
 

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