on a engine that losses "all" compression with heat, it is better to run the engine "rich" NOT "lean" as lean will just get it hotter faster which will make LESS compression, rich will keep it cooler and the compression will stay tighter...I will run a pinched engine several times before buying a new p/s...one of my sponsors does pinching locally using rayaracings tooling and I just send him my motor when it starts acting up he snugs it I run it a couple gallons he snugs it again etc etc etc....and to be honest his engines run twice as good as any new engine I have ever owned....