Oil loss through breather pipe

[tjcassar]

Hi Tom,
The bad news is that there is no wire in the front cylinder exhaust return pipe. ( The one which is easy to remove) So I presume that the others too lack this. I have in the meantime purchased some 0.5mm piano wire from our local model shop which is equivalent to approx 2 thou of an inch. I will have to remove the tank etc to get to the other return pipe attachments. That will take some time. When done I will report results. I am still rather curious about the type of pump you have fitted and where this can be purchased. Obviously, it worked for you so I see no reason why it should not work for mine!! I tried to get a PCV valve this morning from some local car parts shop, but they do not have any. I will now try the Matchless owners club, they will surely know of the one for the G50 Matchless.
Once again Thank you for the trouble you took to help me solve this annoying oil discharge issue
Cheers Tony

 

[Albervin]

Be careful! Over 90% (estimate) of us make do with single start pumps. Twin starts were specifically made for Picadors that had to run at 6000 rpm for 12 hrs to meet MOD guidelines. I believe (please correct me) that Lightnings can run happily on
single start oil pumps.

 

[timetraveller]

Oh Dear! I can see that new boy Tony is going to get more advice than he can handle. I have fitted twin start oil pumps to all my engines for years, both racing and road. My idea is that it gets the oil to places that need it more quickly and anyone who looks at the oil returning through the opened cap on the oil filler neck will see the spasmodic blob-blob of the returning oil. Yes the single start pump will work very well and Ron Vane told me years ago that he used such a pump on 'The Thing' when he broke the world record. Many other people are also very happy with the original pumps. However, and this is where I start to disagree with Tom, removing the metering wire should not cause the problems which you have. It is very simple really, the capacity of the return side of the pump is much larger than that of the feed side and indeed if it were not then the whole system would quickly fail. Consider as well that the return oil is picked up only from inside the chamber behind the crankcase scraper. The whole system relies upon that scraper getting all the oil that is flung from the flywheels, which in turn pick it up from where ever is comes from, and collecting it for the return. In fact there are many of us who believe that the oil metering wires should be removed to allow more oil to flow down the push rod tubes and help to lubricate the cams and followers. Poor Tony is now going to get some conflicting advice.

I would not dismantle bits on top of the engine and replace metering wires. They should not be necessary. Instead I would go for a ride of a few miles and then as soon as you get back drain all the oil from the crankcase and see how much you have. There should be very little as the flywheel/scraper and over-sized return pump should be keeping the inside of the crankcase relatively dry. Even allowing for drain down of internal surfaces you should not have more than, say, about a cup full. More than that and there is a problem. In principle the feed side of the pump cannot push round more oil than the return side can pick up so it should not matter how the oil is being circulated, the crankcase should stay relatively dry. If you are getting a build up of oil in the crankcase then you should be looking for either a badly fitting return pump, a partial blocking of the feed to the return pump possibly due to gasket sealer or broken bits of metal getting into the feed or the return pipe from the pump which goes over the cylinder heads etc being partly blocked. It does not need very much gasket sealer in a pipe or banjo bolt to cause a blockage as the Vincent pump is not designed to give any significant pressure. Happy hunting

 

[BigEd]

Dear Tony,
The wire in the holes is to reduce oil to the valves. This is a good thing if you have a smoky exhaust due to worn valve guides. The wire, if fitted also reduces oil to the cams as the oil from the valves drains down the push-rod tubes and onto the cams. This is not so good for the cams.
If you have a single start pump and the exhaust is not smoky then you probably don't need to fit the restrictor wires. In Tom's case with a two start pump and a lot more oil in circulation the wires seem to have been part of a successful solution.
I think that the valve Tom mentions on the G50 is an assembly in the hollow drive side main shaft. I don't think that it would be easy to fit something like this to your engine.

The simplest thing to do for you might be to try to route your breather pipe upwards and then into a catch bottle so that you can see how much oil is being blow out. Put some more miles on the engine. Monitor the oil in the catch bottle and see if the oil problem improves. You will at least be able to enjoy riding the bike before deciding if you need to do more modifications.

Hi Tom,
The bad news is that there is no wire in the front cylinder exhaust return pipe. ( The one which is easy to remove) So I presume that the others too lack this. I have in the meantime purchased some 0.5mm piano wire from our local model shop which is equivalent to approx 2 thou of an inch. I will have to remove the tank etc to get to the other return pipe attachments. That will take some time. When done I will report results. I am still rather curious about the type of pump you have fitted and where this can be purchased. Obviously, it worked for you so I see no reason why it should not work for mine!! I tried to get a PCV valve this morning from some local car parts shop, but they do not have any. I will now try the Matchless owners club, they will surely know of the one for the G50 Matchless.
Once again Thank you for the trouble you took to help me solve this annoying oil discharge issue
Cheers Tony

 

[John Appleton]

Oh Dear! I can see that new boy Tony is going to get more advice than he can handle. It is very simple really, the capacity of the return side of the pump is much larger than that of the feed side and indeed if it were not then the whole system would quickly fail.

Norman, I agree with much that you have said but-----what Tom is saying is correct. If the larger scavenge pump adds part of its return feed into the crank case, this increases the volume of oil making its way into the sump above that being delivered by the feed side. Now, if Tony already has a two start pump fitted, and if he has no metering wires, then the effect is a two start feed pump and a single start scavenge pump. Nothing is ever straight forward is it?

I have never checked, but I was told at one time, by the man who made them, that the oil holes in the ET100/1 rocker feed bolt were of a smaller diameter than those in the original ET100 so that metering wires were no longer required. As I said, I have not checked recently to see if this still holds true, but that is what Tony Maughan advised me in 1985 and it may well be advisable for Tony to check before he cuts off too much oil.

John

 

[Howard]

Tony

I told you you could get all the answers here. What I forgot to say was that if you ask 100 VOC members a question about Vins you'll get at least 200 answers, and most will be right. The problem is, no 2 Vins are the same anymore, and what holds true for one does not for another. Listen to everyone, then try to decide the best option for you.

In my touring days I made 2 trips to Spain (2500 miles) with a 2 start pump and no metering wires. the breather was a large pipe from the ATD cover with a washing up liquid bottle on the end. I lost about a pint of oil for each trip. I've only ever fitted metering wires as a temporary cure for smoke caused by worn guides, because I don't like the thought of starving the rattly bits of the engine. I'm not saying anyones right or wrong, just different opinions.

For what it's worth, you don't know which pump you've got, so I'd be inclined to extend the breather to a catch tank for starters - as per Eddy above.

H

 

[tjcassar]

Hi,
To be honest with you I do not know what pump is fitted in my Rapide, and moreover, I do not know what a two start pump is. How can I find out.
Tony

 

[tjcassar]

Hi Eddy,
Yes, sound advise, I will do just that. As at today I have clocked 600 miles since the rebuild so nit might be too early to start pointing fingers at things. I will re route the front breather and collect the oil that is being pushed out and take it from there. As a point of interest, I do NOT have a smoking engine at all. But I do not have the wire going through the little hole. And only seem to lose oil when I stop and am on idle, say at a jubction or traffic light. At this point, I always leave a puddle. Not even on a total loss system on some other bikes I ride does this happen!! This is how this whole debate started as I was rather surprised to see this mess from such a finely engineered motorcycle. I am now not unduly worried though. Cheers Tony

 

[John Appleton]

Tony, you are quite right in not being unduly worried. As you have already seen, it would be easy to involve yourself in complex modifications and still not cure the leak. The best way is to enjoy the ride and see what developes. As to your question regarding the two start pump, the vincent engine is fitted with a rotary plunger type oil pump. This plunger has a helical groove machined around it and a fixed pin locates in this groove. The plunger is rotated by a worm mounted on the timing side main shaft. As the plunger rotates it also goes up and down due to the pin in the groove. This up and down action is what pumps the oil. With a two start pump the worm has two driving spirals instead of one. This doubles the speed of the pump, and obviously doubles the amount of oil in circulation. I have yet to hear of a standard pump being inadequate, and have never heard anybody say that a two start pump has improved anything. It was developed for the aircraft engine that was expected to run at fixed high revs. and not for road bike use. I would be reluctant to start fitting metering wires to the rocker feeds until you determine what type of feed bolts have been installed as some of these have a reduced hole size to make the wires unnecessary.
You appear to have come to what I believe is the right conclusion-- learn what you can and make up your mind when you have gained a bit of experience with the bike.
John

 

[timetraveller]

Hi John, your point is well made and I am sure that you are correct. However, the extra oil is only that which can get through the four small holes in the rocker feed bolts. Compare their combined cross sectional area with that of return pipe or even that of the four holes in a banjo bolt, noting the low pressure in the system and it is difficult to see how this amount of oil is going to overload the return side of the pump. What ever we think the theory is, none of my bikes with twin start pumps and no metering wires build up oil in the crank case and oil being pumped out of the breather at tick over in large quantities is not normal. A small amount almost certainly is nothing to worry about. Tony can easily tell which pump he has by looking inside the filler cap of the oil tank and seeing the returning oil when the bike is ticking over. If it is a blob every second or so then it is a single start pump, if it is more than that then it is probably a twin start. Additionally, if it is a twin start then almost certainly someone will have fitted a small deflector under the screw on top of the boss that the returning oil emerges from as at higher revs there is enough flow to cause splashing and this will get past the seal in the oil filler cap and cause oil to eventually cover the top of the engine. In the mean time I agree that Tony should continue to ride and enjoy the bike. Pity to waste all that riding in sunshine time.