I've never seen a large variation on fixed timing unless points were really faulty or condenser was badly connected or coil was shorting,and these things usually cause misfires and weak acceleration.This question is one for someone like Fred or Ron or Ree I think.I suppose worn crank bearings(mains)could cause the points to deviate also.Ron is a Motobecane guy and maybe he's run into it.I'd check coil wire and connection,points condition(spring tension and for dirt),and do Ron's ohmmeter test on the condenser,in lieu of better advice from the Gurus.Glad I don't have THAT problem.BYE!