Slight oil leaks due to synthetic oil?

[Dr.T]

Where is the cam chain tensioner? Thanks for the replies. I'll post some pics in a little bit.

[jeff.saunders]

Amsoil is good oil. Hope you used the motorcycle or diesel engine variety.

Synthetic oil does not cause leaks, however they may exploit weak gaskets.

How gasket materials reacts to different liquids determines how effective the gasket is.

A couple of years ago I did a massive amount of research on gasket materials as we were having gaskets made for us. What I found out is each gasket compound expands different amounts based on the liquid it is exposed to. After doing all the research I had a mix of gasket materials and exposed them to different oils and also gasoline. Some of the gasket material expanded 60% or more (and that is good - you want a gasket to fill the imperfections between surfaces). A couple of the materials didn't seem to like synthetic oil - the amount of expansion was way less that with mineral oil.

So... I think some of the gasket material in older bikes has very limited sealing properties when exposed to synthetic oil.

[78gs750e]

cam chain tensioner is on the back of the cylinders under the carbs

[1948man]

Possibly a leak where the tach cable goes in?