2005 R850R oil leakage
 

Hello everyone,

I recently bought a 2005 R850R with about 20000km. When I did a first "light" service (oil/spark plug change, battery charging, changed filters, no cylinders/cylinder covers were opened etc), I got an oil leakage at the right cylinder.
When I ride up to 1/2h with low rpm (<4000) nothing seems to happen. When I ride at the highway for longer than 1/2h with a medium or high speed oil starts to leak on my boots, and the bottom of the right cylinder soon becomes full of oil. If I stop then, some drops fall to the ground for a while. I cleaned up the cylinder several times to watch where the oil comes from. It probably comes from the camshaft sprocket cap since it is the first that starts to fill with oil and a nut underneath this cap is the first point where oils starts to drop. I had taken a relatively long ride before having the service and did not notice anything (maybe the oil level was low by then, did not checked it).
What are the most possible oil leak sources in this case? The camshaft cap or the O-ring inside it? the gasket at the cylinder head (valves cover?). The gasket at the bottom of the cylinder seems clean. Is there a chance that there is a "more internal" problem?
The previous owner must have had an accident and the top of the cylinder is slightly scratched. Do you think a fall he may had, has "shaked" somehow the cylinder and affected something inside?

There is a circular rubber around the sparkplug that can cause leaks if not replaced properly (It needs to be fitted to the cover) the rubber cover gasket is reusable, but if a small piece of grit has stopped it from sealing? There is an O ring around the circular cam cover that may have split, the problem with finding these leaks is that the wind moves the oil around away from the source, the rocker cover bolts are prone to stripping the threads in the head if someone has been too strong.
Stewart