I may or may not have a problem with my 1939 Ariel OH 250. Hope someone on here can help:
The bike is a 1939 250 OH with a 350 Hartley alloy barrel, Hartley gas flowed head, higher compression piston, larger inlet valve, Hartley cam etc etc. The engine was built in the early 1950s and I rebuilt it this year - it was seized after standing in a shed for donkey's years.
Following its MoT and a few short rides a couple of weeks ago I took it for a fifty mile ride today. I noticed that after about 25 miles the oil pressure gauge had dropped from the 10 PSI it was showing once warmed up and cruising at 50 MPH to next to zero. When I shut the throttle the pressure rose to 5 PSI then dropped again to virtually zero. At tick-over the gauge was not registering anything.
I looked at the oil return in the tank to see what was happening as I know gauges are notoriously unreliable (It's the original item). At tick-over there is a fairly good return but when revved quite high the return seems to drop to next to nothing.
Despite the oil issue the ride home was fine and there were no untoward noises, the engine didn't get overly hot or show any signs of distress.
So, my question is; am I worrying about nothing or is this a fault somewhere in the engine. It has a new uprated oil pump from Draganfly and I put two of the small round paper washers round the quill feed to make sure it was air tight, all bushes seemed to be unworn and I am running it on Morris Classic straight 50 and intend changing to straight 30 for the winter. While I can't see how it could have had an effect on the oil pressure I'd better mention the exhaust rocker inspection cap fell off sometime during the first half of the trip!
Any help gratefully received!