Bill, once again I've had no personal experience of a problem as extreme as this. Timing covers do get quite hot after a long run depending on ambient conditions.
It seems to me that you either have a far too lean mixture, retarded ignition timing or excessive internal friction.
Did you run with the same carb set-up before the rebuild ?
Is the oil circulating correctly, especially the head ? How did the top end look when you dismantled ? Any signs of heat damage on the moving parts ?
I think that I would keep coming back to ignition timing but I don't know where as you seem to have double checked everything. Is the Sparx rotor correctly marked ? Timing plates are often incorrect but your problem is extreme. Have you checked the timing with a degree disc ?
Fingers crossed for you :?
It seems to me that you either have a far too lean mixture, retarded ignition timing or excessive internal friction.
Did you run with the same carb set-up before the rebuild ?
Is the oil circulating correctly, especially the head ? How did the top end look when you dismantled ? Any signs of heat damage on the moving parts ?
I think that I would keep coming back to ignition timing but I don't know where as you seem to have double checked everything. Is the Sparx rotor correctly marked ? Timing plates are often incorrect but your problem is extreme. Have you checked the timing with a degree disc ?
Fingers crossed for you :?