Oil between inner and outer timing covers

[KCF21]

Today I have been for a ride on my newly rebuilt 1967 BSA C25 Barracuda after a break of some months during which I have been changing fibre washers for ones made from Klingersil sheets (not all fibre washers are equal!). After 10 miles or so I noticed that hot oil was "pulsing" from the engine breather pipe and soaking engine, ground and back tyre. Logically, this means that there is oil getting into the space between the inner timing cover and the outer timing cover. As I understand it, oil should not be in this space at all (other than a "mist"?) so where is the oil coming from? I think that the only place that it can be coming from is past the camshaft oil seal; do you agree with this logic? If this is so, then the solution is to take the engine apart and inspect/replace this seal?

Some background information
1. the oil in the tank was slightly high when I started the ride, however, this had dropped to below the "low oil" level by the time I had got home (there was oil in the bottom of the tank, just showing on the dip stick so no damage should have occurred to the engine, I hope!).
2. there was a good oil return to the tank before I started the run.
3. the breather was clear, this was something checked on rebuild.

On an earlier ride (following the rebuild), I did have a problem with oil escaping in a similar fashion from around the gear change quadrant spindle (also "pulsing" from the spindle), this was addressed by an engineer making a sleeve for the spindle that fits between the inner and outer timing covers with an "o" ring on either side. On that occasion we noticed that the camshaft oil seal was not the correct size and so this was replaced. Clearly, the root cause of the internal oil leak has not been cured. I guess that by stopping the oil getting past the gear change spindle it has risen high enough to come out of the breather. Today I took off the contact breaker cover, which now covers an electronic ignition unit, and this was holding back a significant amount of oil proving that the space between the inner and outer timing covers was completely full of oil.

Any thoughts, advice, shared experience would be helpful,
Rev Kev

[Daz]

  The space between the inner and outer timing covers is effectively an oil catch tank. The engine breaths throught this space via the timed hole through the camshaft. Any oil collecting in here should be drawn back into the engine through the small hole low down in the inner timing case, I suspect this may be blocked.

[KCF21]

Does anyone else have any thoughts on this?
Rev Kev

[Janacek]

Don't know this model,but on Gold Stars there is a timed breather for the timing chest.Is it possible that it has been assembled incorrectly.
Once had a Triumph with a similar problem.The Triumph had a disc valve breather with a hole in the disc which had to line up with the correct piston stroke.It was easy to fit the disc upside down, with the result that oil would be forced into the combustion chambers and the engine would stop in a cloud of smoke.

[Daz]

Don't know this model,but on Gold Stars there is a timed breather for the timing chest.Is it possible that it has been assembled incorrectly.
Once had a Triumph with a similar problem.The Triumph had a disc valve breather with a hole in the disc which had to line up with the correct piston stroke.It was easy to fit the disc upside down, with the result that oil would be forced into the combustion chambers and the engine would stop in a cloud of smoke.

The timed breather is built into the camshaft on the unit singles so if the valve timing is correct the breather timing will be aswell.

[Daz]

 The space behind the points cover is sealed (or should be) from the space between the two timing covers. The camshaft oil seal may have failed or been pushed out of position.
 I would check again that the oil pump is returning the oil to the tank, there should be oil and air bubbles. The engine may be filling with oil and overwhelming the breather system.

[Tigerfeet]

I notice you mentioned the bike is newly rebuilt. I would check that the oil pipes are correctly connected. I believe that on some BSA 250s the pipes go direct, and for other models the pipes are crossed over.  (See RR Pg36.)