Andrea sent me these photos to post from a bike that was resuscitated. Here is Andrea’s explanation of the photos:
As you can see, on the first picture of the engine the leaking is coming from the front and rear cylinder just below the spark plug. It is exactly where it is located the head gasket.
The bike was sitting in a warehouse for ages, and I bought for less than $ 1,000 . I found it had a bad connecting rod bearing. Now it is perfect.
..note the sludge in the crankcase.
I hope these pictures will help…
It just goes to show that even fairly significant problems in our PC800 engines (very rare!) can be fixed with just a little effort. Thanks for the information, Andrea!