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Oil loss through breather pipe

tjcassar

Well Known and Active Forum Website User
Non-VOC Member
Hi, I am new to Vincents, have purchased a 1950 rapide which is completely rebuilt, running in at the moment first 500 odd miles and loosing plenty of oil especially from the front crank case breather, lost 1 ltr of oil in 400 miles!! Plenty of oil escapes especially noticed when ticking over after run!!! Is this normal?? Or could I have parts missing in the breather? Any help to solve problem would be appreciated.
Tony
 

Howard

Well Known and Active Forum Website User
VOC Member
Hi, I am new to Vincents, have purchased a 1950 rapide which is completely rebuilt, running in at the moment first 500 odd miles and loosing plenty of oil especially from the front crank case breather, lost 1 ltr of oil in 400 miles!! Plenty of oil escapes especially noticed when ticking over after run!!! Is this normal?? Or could I have parts missing in the breather? Any help to solve problem would be appreciated.
Tony

It sounds as though the timed breather may not be timed correctly, but it could be other problems.
You will find lots of threads about breathers on this site it's a common topic for discussion.
Join the VOC and you can draw on the experience of other members, it's a fairly certain, that if you've got a Vincent problem, someone's found a solution to it.

H
 

Albervin

Well Known and Active Forum Website User
VOC Member
Rebuilt with what?

Hi, I am new to Vincents, have purchased a 1950 rapide which is completely rebuilt, running in at the moment first 500 odd miles and loosing plenty of oil especially from the front crank case breather, lost 1 ltr of oil in 400 miles!! Plenty of oil escapes especially noticed when ticking over after run!!! Is this normal?? Or could I have parts missing in the breather? Any help to solve problem would be appreciated.
Tony
Wow! That sounds like me 30 years ago.. I bought a Comet from a well known dealer, totally rebuilt. Unfortunately it was from second hand parts & beer cans (true!! the lock washers in the timing chest were from cut down beer cans) & it lost the contents of the oil tank in 150 miles! Unfortunately the dealer is still plying his trade in Twyford. (O:confused:OPs, is truth still a defence for libel?)
It is "breathing" too much due to poor ring sealing, incorrect breather timing or a combination of things that will cost a lot of money &/or time. Find someone nearby who knows Vincents & make him your best friend.
 

Albervin

Well Known and Active Forum Website User
VOC Member
Wow! That sounds like me 30 years ago.. I bought a Comet from a well known dealer, totally rebuilt. Unfortunately it was from second hand parts & beer cans (true!! the lock washers in the timing chest were from cut down beer cans) & it lost the contents of the oil tank in 150 miles! Unfortunately the dealer is still plying his trade in Twyford. (O:confused:OPs, is truth still a defence for libel?)
It is "breathing" too much due to poor ring sealing, incorrect breather timing or a combination of things that will cost a lot of money &/or time. Find someone nearby who knows Vincents & make him your best friend.
Right. Probably not too many Vincents in Malta. Join the club & gain access to a font of knowledge. It is important to know who to turn to when you have such problems because it is very easy to waste a lot of money going down the wrong road.
 

Howard

Well Known and Active Forum Website User
VOC Member
Wow! That sounds like me 30 years ago.. I bought a Comet from a well known dealer, totally rebuilt. Unfortunately it was from second hand parts & beer cans (true!! the lock washers in the timing chest were from cut down beer cans) & it lost the contents of the oil tank in 150 miles! Unfortunately the dealer is still plying his trade in Twyford. (O:confused:OPs, is truth still a defence for libel?)
It is "breathing" too much due to poor ring sealing, incorrect breather timing or a combination of things that will cost a lot of money &/or time. Find someone nearby who knows Vincents & make him your best friend.

I think a few of us must have started with Vincents in this way ....... what is "rebuilt" "refurbished" "restored" etc?

I wonder why we stick with Vins for so long, when we start off on a bad footing - 36 years this year for me, and still cursing Slater Bros "rebuild" but enjoying the bike.

H
 

tjcassar

Well Known and Active Forum Website User
Non-VOC Member
It sounds as though the timed breather may not be timed correctly, but it could be other problems.
You will find lots of threads about breathers on this site it's a common topic for discussion.
Join the VOC and you can draw on the experience of other members, it's a fairly certain, that if you've got a Vincent problem, someone's found a solution to it.

H
Thank you for your advise, I will certainly join membership.
 

BigEd

Well Known and Active Forum Website User
VOC Member
VOC Forum Website Moderator
Oil loss through breather pipe.

Who did the rebuild, what work was done and how well was it done? If the rebuild was done competently and included new pistons it could be that the rings and bores have not yet fully bedded in. The timed breather should close 30 degrees after bottom dead centre measured on the rear cylinder. You can check this without a major strip down by removing the brass OP9/2 oil delivery quill and mounting a degree disc on an extension rod pushed in to the timing side mainshaft. Put a length of tube on the breather pipe and blow through it as you turn the engine. When the rear cylinder gets near to 30 degrees after bottom dead centre you should find it becomes difficult to blow. It worked for me when I checked my breather timing. I posted something on breathers last year and I have pasted it below to save you searching.
We were in Malta a couple of months ago. We flew there and then got the ferry to Gozo where we stayed at a house in Xaghra belonging to our eldest daughter. A lovely place to visit although the roads are quite bumpy in places.

“Here is my experience with my '48 Rapide, built from (what seemed like a million) battered bits that had returned from Argentina. I got it registered and back on the road last September, i.e. just over 12 months ago. I'm still getting the bugs out but having put on 10,000 miles there are hopefully not too many bugs left to sort. I used a standard timed breather set-up initially and this was pretty oily. As the new pistons and bores bedded in things improved a little.
There were/still are various weeps and drips from poor joint faces. Modern sealants have reduced these significantly.
I re-routed the breather pipe straight up and over the top of the engine and into an approximately half pint plastic catch bottle. Over two to three
hundred miles the bottle maybe collected a quarter pint of oil/watery emulsion.
The next mod was some sort of car PCV valve bought cheaply on ebay and plumbed into the rear cylinder exhaust rocker cap. Several people on list have done a similar modification. This breather was also routed to the catch bottle so that I could monitor the effect. The result is that the catch bottle now collects very little. Over the last 1500 miles it has collected perhaps two egg cups of oil/emulsion.

Summary: On my machine the PCV valve seems to have improved the breathing.

I still have the original breather operating so maybe I could try plugging this and see if this is better or worse.”
 

Tom Gaynor

Well Known and Active Forum Website User
VOC Member
My oily plugs (after 200 miles the front one had the electrodes hidden in a carbon slag heap) were completely cured by oversize OD liners in rebored muffs, and new pistons. I was told, by Trevor and others, that the muffs gradually lose their grip on the liners, and that the interference between the two is essential. I'm now completely certain of this. Wear is one issue: time is another.

I subsequently replaced the valve guides with new sealed ones, but it was the bores that made the big difference. None of this made much difference to oil consumption, because oil was being chucked out of the breather. After a great deal of faffing about with standard timed, standard with extended timing, standard series D, and series D with a non-return valve breathers, I realised that the problem was too much oil UNDER the pistons, in the crank chamber (put there by my two start pump). So I put the restrictor wires back IN to the rocker feeds, and the problem virtually went away. The scavenge now empties the crank chamber without the rocker feeds dumping it back in again before it ever reaches the oil tank. I detailed this in the last MPH.
I am now convinced that had I concentrated on reducing the clearance between piston and liner, and not dealt with the lack of interference between muff and liner, I'll still be faffing about with breathers.
Incidentally my final breather system is identical to the one Eddy arrived at, but with the timed breather plugged.
 

tjcassar

Well Known and Active Forum Website User
Non-VOC Member
I do not know who did the rebuild as I purchased this machine at the Bonhams Staffors sales. But I understand from a British friend of mine who knows who built it, that he is a knowledgable person. The cylinders, pistons and rings are all new and the bike has only covered 400 miles. The worst breathing of air and oil takes place when the bike is hot and is on idle. The oil is sprayed out via the front breather just above the distributor as mine is coil ignition 12V. this breather is just a bunjo bolt with no non return valve at all. Is this normal??
Re Breather valve, is this in the crank case?, I will try to see if I can manage to check when it opens and closes as suggested by you.
Gozo is a nice place to spend a quiet week. The roads throughout these islands are a disaster, we go off to Sicily and Italy on rallies there to show and use our bikes.
Would appreciate any help you could give me to try to solve this mess my bike creates.
Cheers. Tony
 
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