1957 B31.What size holes should the banjo bolts have for rocker oil feed and return be?
Mine has the same size tiny hole in all three bolts,rocker feed and return.
The return banjo bolts should be at least twice as big as the feed.
When I looked into this a couple of years ago I concluded that the rocker bolts 65-317 were 1/64" dia and the drain pipe bolts 3/32" dia (ie: several times the combined area of the rocker bolts to prevent accumulation - although I suppose some goes down the pushrod tube). 1500 miles later everything looks OK up there.
There should be 4 banjos. Make sure both return banjos are the 'large' one. I had a terrible smoking on my B31 when I got it. Turned out the bottom return banjo bolt (into the crankcase) was a 'small hole' feed one. Had to partly remove the primary to get it off and drill it out. I did shorten it slightly before refitting so I could remove it easier in future should I ever need to. It was plenty long enough.