Timing Cover - Contact Breaker oil seal, Sorted at last!

There should be no issue with oil on the Tri spark PIck Up. Obviously if it becomes  awash with oil then there Might be an issue. The is an issue with significant oil on points. But many miles have to elapse first.  Yes cure excessive oil flow, but it will NOT stop the engine initialy.

Very helpful post. I've always had leaks with O.E. seals and three different cams. Checked the dimensions and concentricity, all OK. Oil exits through the bottom drain hole and back along the cases onto my boot and trouser leg. Minimal but annoying amount noticeable on long trips  

Fitted a drain to a small catch can on the lower frame which works great but shouldn't be needed and I like the Trispark clean and oil free even though the hot oil has no effect as Alan says.

I've ordered one £2.36 delivered from ebay and hopefully it'll work on my bike.

Several years ago (In the 70s I rode a good few miles) I had a Commando engine (in Fbed frame)  That did this very thing. dribbled oil out of the Points cover cap. We were standing in the T queue at the M way Services, when my Pal who rode a oil tight Boxer twin, became a bit concerned his right boot had a splattering of oil. He rushed out to his bike, which also had a slight splattering on the front RHS. I then pointed out that I had similar on my right boot. We all know where it was originating from. (he was following me)  But I had my comeuppance as within a few days of riding the points burnt with the oil, advanced the ignition, burnt a hole in a piston.  You are safe for a few miles only! Keep away from points!

The standard seal will work, however the quality of that portion of the cam that runs in the seal can leave a lot to be desired. Tapered, oval, undersize and not concentric are usually the case so worth checking that area. 

A properly machined cam should have none of those defects on a 1/2” long cam seal surface unless you used a stone axe!  That would be unacceptable on the ancient Colchester I learned on at the start of my apprenticeship. 

The SS marked Combat cam (as per Dyno Daves cam data) in my bike when I bought it, had marks from previous “attention” near the ignition thread but the seal area was even and unmarked.

My new USA Johnson J380 and Web#312 cams were ground to a very high quality finish all over and wouldn't suddenly become tapered, oval, undersize or not concentric. That can only come from substandard original machining or damage. Didn't stop all three cams leaking with O.E. seals however.

Do you have the actual tolerance for the diameter of the cam at the seal face according to your own cam information? As far as I know the basic dimension is 0.625”∅  possibly ±0.001”

There's a product called a seal saver that most bearing factors can supply. It's thin steel sleeve with a smooth hard chrome plated outer and they come in all sizes imperial and metric. It comes complete with a tube for installation. The only difficulty I've found can be removing the fitting lip on the end seal saver, however this can be left on if it's not interfering with the seal.

Sadly when replacement OE cam seals keep leaking and the shaft surface is in good nick the cause can be a worn cam bush.

Was it in the old NOC Service Notes that there was a reference to the factory-fitted red rubber seals (which had a steel outer) and that they were much better than the harder black synthetic seals which were generally supplied by the trade?...What is OE in this context ? I bought a small supply many years ago and they have never given trouble...I did have a new timing cover though that had a porous casting fault from inside to the points lead tunnel. That confused me for a while.