Ariel Owners Motorcycle Club

On route to a New Zealand Ariel rally a couple of months ago, the VB return pump failed approx 30 miles from my destination. I did not detect anything amiss until I arrived and noticed a growing puddle of oil under the bike.
In that distance it had pumped about half a tank of oil onto the road and all over the rear of the bike. It had also filled the magneto with oil and yet the old girl did not miss a beat. While it was idling, there was oil peeing out of the points cover !
I stripped the pump etc and cleaned everything out as best I could while at the motor camp accommodation ( found nothing at all in the return pump; perhaps a slight mark on the ball bearing seat, but no dirt etc) and did complete the rally the following day without problems.

On return home, I found that, not only was the mag full of oil, the fabric wrapped dynamo field coil was absolutely saturated and proved impossible to get clean.

I guess a positive is that I now know that my feed pump works really well

I am now wondering if I should remove the rubber washer that is between the timing case and magneto so that if the return pump does fail again, at least it may be less likely to contaminate the magdyno.

Cheers,
Bevan

For what it's worth, I 'd leave the rubber seal in place. The amount of oil that
comes out in normal service with the seal failed is more than enough to
cover the timing cover, gearbox, footrest, kickstart and gearchange, not to
mention right boot and trouser leg.

The seal also serves to keep water and other rubbish out when the engine is
stopped.

Most magdynos have small holes underneath which I assume are there as
breathers and drains. When I've had pump problems the magdyno has usually
drained itself once going again.

Older engines have a lower second breather in the timing case. I read or was told that its purpose was to limit the oil level in the timing case when something goes wrong. The other breather also found on later engines cannot protect the mag because it's too high.