E: Engine Oil Tank Breather Advice

[davidd]

Speedtwin,

Yes, the breather was used to direct oil and oil mist to the chain. The chain oiler can be blocked by installing a Vincent oil drain plug. This is sometimes useful if you replace the original oil drain plug with one that has a magnet in it.

The oil breather holes in the filler neck cannot be blocked off with ease. There are two of them and one is not easily accessible. There is a hole on the timing side of the rectangular chain oiler block that is barely visible. It is a bypass for the chain oiler. It prevents you from directing too much oil to the chain oiler by returning oil to the tank. There is a huge amount of oil being splashed about in the tank at higher RPMs due to the poor direction of the oil return hole. The oil is splattered against the filler neck and it is often pushed out of the oil cap vent hole.

The oil caps were vented and it is important to me to have one. I enlarge the vent hole a bit on the racers by drilling the hole a hair larger. A downward deflector in the oil cap is useful if the oil continues to weep out of the cap vent hole.

I doubt that a deflector is necessary, but it was important for me. The chain oiler block is brazed into the filler neck and it was done by eye. The height of the block varies considerably, so the height of the block needs to be checked. Otherwise, you run out of clearance with the bottom of the oil cap. There was a loop on the bottom of this cap and I used a cotter pin to hang the deflector from it.

David

 

[Speedtwin]

Thank You David,
You have answered my next question on the chain oiler and the bleed back to the tank when shut off, nice modification of the cap your oil deflector is a stroke of, I now have a use for all those little Honda pistons I have squirrelled away.

 

[Bobv07662]

When I first put my Rapide on the road the old girl was a heavy breather out of the timed breather. The largest reduction in that leakage came after I increased the size of the vent hole in the oil cap. David has offered great advice!

 

[Speedtwin]

Thanks Bob,
I shall be replacing the oil tank chain oiler bung getting the de greaser out for a hard clean, drilling the vent hole and fitting a deflector.
The machine is fitted with upper breather for the heads and a timed breather.
Nice neet job blowing out to the left hand side rear of the bike.
Seems pretty oil tight in general all over.
As a good friend said to me oil on the floor indicates oil in the bike...

 

[b'knighted]

As a good friend said to me oil on the floor indicates oil in the bike...

No, it merely indicates that there was once oil in the bike. If you always park in the same place the oil on the floor may not be that recent. If your bike does develop a leak the oil on the floor will give little clue as to where the leak is, just where it is dripping from.

I take a different view. My bike doesn’t leak. It does like to mark its territory.

 

[Speedtwin]

Sorry should have said "No oil on the floor no oil in the bike"

 

[A Nut]

Just a thought. If there is a leak from the chain oiler especially if the adjustment screw in the neck is screwed down tight it may be that the pipe from the neck down to the exit from the rear of the tank is fractured inside the tank. If the oil level is above the fracture it will leak out. I had this on a section members bike and I blanked it off as described. I never use mine anyway but regularly oil the chain with spray lube.
Brian

 

[timetraveller]

Mr Speedtwin,, Sir, if I have understood correctly you haave the timed engine breather and another breather on either the tappet covers or valve spring caps. If that is correct then when the pistons are going up and the engine breather is shut the engine can suck air in througth the top breathers. This is not good for several reasons which should be obvious. One or the other but not both.
Regarding a deflector inside the oil filler cap; I cut a piece out of the side of a 'baked bean' can, made a hole in one end and held it in place with the adjusting screw and spring for the chain oiler. It is tin plated, nicely curved to act as a deflector and completly prevents oil splash on a twin with a two start oil pump.

 

[Peter Holmes]

Off topic (once again) if you want to solve chain oiling problems once and for all, purchase and install the latest electronically controlled Scottoiler, infinitely adjustable, once set no more adjustments required, chain always clean looking and well lubricated, and not a splash on the rim or rear tyre, as you can probably deduce, I am very impressed with this bit of kit. Only fitted on the twin at the moment, the Comet will follow soon.

 

[Speedtwin]

All my breathing is out the top .
My typing mistake..
Scotoilers are indeed the business I have used and fitted them for many years on chained machine I prefer belts and shafts this weather.
Art from the Vincents of course..