I know this is elementary and I’m sure Minivin knows it but newer owners may not. Habitually parking on the left side prop stand causes oil to migrate from the crankcase into the chaincase. At the first right-hander it sloshes out of the hole behind the clutch and covers the rear tyre. Also a faulty chain oiler will empty the UFM remarkably quickly. If the tapered metering screw (standard Amal pilot air screw) has a shoulder on it then it will pass a lot of oil. Even screwing it down hard does not seem to stop it. New ones are available and not expensive.
Who makes this breather?
- Thread starter minivin
- Start date
To stop the clacking from the nylon ball, simply add a short piece of rubber pipe (I used car-heater hose with a convenient right-angle bend incorporated) to the exit end of the system up under the petrol-tank; and then add a simple plastic compressor-silencer to the end of said pipe. It has worked for me for 30-odd years. No clacking 
Peter B
Bristol, UK.
Peter B
Bristol, UK.
On the other hand Peter, iv'e found it better to hear the nylon ball. The reason is that my Prince has a Mac Read breather and i started to notice that the engine was starting to push oil out of the pushrod tubes. After mumerous attemps to cure the oil leaks "a big bright star appeared above my head" and i realised i could'nt hear the ball. When i took the breather off the timing cover it was stuck solid with white sludge and took ages to free it off but cured the leaks.
My Mac Read/Ivan Caffery breather also produced mayonnaise along with clacking, I always thought that it would have been far better with a small reed valve somewhere in the system, maybe built into a modified ATD inspection cover, but not being an engineer I could not work out how best to make it.
That was also one of the bits I just refitted, must check that later!
Rob
You know the problems I had with my Comet as well as anyone!!! Mine pumped oil out of the top end and fouled plugs for ages. I had the muff relined and bored out to suit the 40 thou oversize piston with new rings and thought that might clear it up as everything else had been done. Still fouled plugs, though. The thing that eventually stopped the oil problem was finding out from various Vincent bods that there should be an ET234 brass disk about 10mm diameter and negligible thickness behind the inlet oilseal in the timing case cover. When I looked in mine there was nothing there which meant that far too much oil was getting up to the head. Knowing how long you have been at the Vincent coalface you have probably checked this already...... but it solved the final problem for mine. Phil
You know the problems I had with my Comet as well as anyone!!! Mine pumped oil out of the top end and fouled plugs for ages. I had the muff relined and bored out to suit the 40 thou oversize piston with new rings and thought that might clear it up as everything else had been done. Still fouled plugs, though. The thing that eventually stopped the oil problem was finding out from various Vincent bods that there should be an ET234 brass disk about 10mm diameter and negligible thickness behind the inlet oilseal in the timing case cover. When I looked in mine there was nothing there which meant that far too much oil was getting up to the head. Knowing how long you have been at the Vincent coalface you have probably checked this already...... but it solved the final problem for mine. Phil
Phil, I'm a bit confused. A brass disc behind the inlet oil seal?
Phelps.
You know the problems I had with my Comet as well as anyone!!! Mine pumped oil out of the top end and fouled plugs for ages. I had the muff relined and bored out to suit the 40 thou oversize piston with new rings and thought that might clear it up as everything else had been done. Still fouled plugs, though. The thing that eventually stopped the oil problem was finding out from various Vincent bods that there should be an ET234 brass disk about 10mm diameter and negligible thickness behind the inlet oilseal in the timing case cover. When I looked in mine there was nothing there which meant that far too much oil was getting up to the head. Knowing how long you have been at the Vincent coalface you have probably checked this already...... but it solved the final problem for mine. Phil[/QUOTE]
Phelps.
You know the problems I had with my Comet as well as anyone!!! Mine pumped oil out of the top end and fouled plugs for ages. I had the muff relined and bored out to suit the 40 thou oversize piston with new rings and thought that might clear it up as everything else had been done. Still fouled plugs, though. The thing that eventually stopped the oil problem was finding out from various Vincent bods that there should be an ET234 brass disk about 10mm diameter and negligible thickness behind the inlet oilseal in the timing case cover. When I looked in mine there was nothing there which meant that far too much oil was getting up to the head. Knowing how long you have been at the Vincent coalface you have probably checked this already...... but it solved the final problem for mine. Phil[/QUOTE]
I'm a relative newcomer to the Vincent engine so learning all the time from those with lifetimes of experience! The small brass disc (ET234) with a 20 thou hole in it apparently restricts the flow of oil to the inlet valve on the Comet. They tell me that it's not fitted on the twin cover because there are two inlet valves to feed. The hole in the timing cover allows too much oil to pass if it's only feeding a single inlet valve, thus an ET234 restricts the flow to a level suitable for the single cylinder engine. It worked for me! Phil
ET234 restricts oil to the cylinder feed. There is no connection with it and the inlet valve. They are about 5" apart. The oil can't get from there up into the head. If by fitting this restricter disc it fixes your problem, odds are that the cylinder feed hole in the sleeve is too high and feeding oil in above the oil ring. This would certainly explain your oil fouled plugs. Put a disc in there without a hole in it in that case. That will also direct more oil to the cam and the crank to.
Oil on the mag cowl has probably come from the head the front left hand cylinder stud (looking from astride the bike) has two threads by which it screws into the crank case, the grove between the two threads is an oil way. When putting in the stud the upper stud the top thread should be coated with jointing compound as oil can make it's way up this thread and cause a mysterious leak onto the mag cowl. I found out the hard way many years ago and in fact it is mentioned in Paul Richardsons excellent bible. Could be the rear l/h stud been a long time since I did it and old fartdom is catching up!!.