I've seen a couple of these breather pipes with similar small holes..... Maybe a short lived factory mod to direct oil vapour to the chain. Hardly effective as most would exit down at the bottom of the tube. Another variant is a short tube running back under the chain guard support web, so oil drips down into the chain, to be immediately flung off as the chain changes direction round the gearbox sprocket. There's always a black oily mess around the sprocket anyway from the sleeve gear bush, so leaving the holes won't make any real difference in my opinion.
To direct the breather onto the inside of the lower chain run would seem to me to be the most effective use of the breather vapours. Later models don't have the tube.... just a hole.
Swarfy
