I cant see thats its poor oiling to the valves. but what do i know. One thing you can do is remove the oil tank cap and put your finger over the oil return jet for a few seconds, that should oil the valves up.
What exactly did the electronic ignition replace, was it a full system, you now have no mag or what?
When it stops does it seem over heated?
Are you using an air filter, if so remove it and try it without.