Ls,
I recently received Roadholder 406 October 2021 in which an article was published with the title as above. I'm always curious to learn anything about the Norton Commando so I quickly read the article.
Symptom 1. Andy writes: "I have had the bike for 25 years, and I remember in my early days of owenership I noted that the oil return to the tank was pretty intermittent, the oil coming out in pulses, but not as a continuous stream. I had no reason not to think that this was normal.
Conclusion 1: This explains the intermittent flow I noticed all those years ago.
When I bought my Norton Commando Fastback more than 40 years ago and overhauled it, I took the oil pump apart. I learned from a friend that the scavenge gears are twice the size of the oil press feed gears.
The return cogs are twice the depth of the feed items, to keep the crankcase clear of excessive oil. ( Stated in Norman White's Norton Commando Restauration Manual).
If one starts the Commando after a few weeks with no anti drain valve, there will be oil in the crankcases and one will see a constant flow but after a while one will see a intermitten flow which is normal with all the Norton twins.
Jan
... with all dry sump bikes the return capacity is greater than the feed so an intermittent flow is normal. I would worry if the return was continuous. As I did when I first had an AMC single with its daft oil pump which only gave a tiny trickle......
Even with an anti drain valve enough oil will usually drain down into the crankcase from the head etc to give continuous flow for the first few seconds.