ORIGINAL: pe reivers
we have 8 to 10% ethanol in our fuel. Running carbs dry will cause the diaphragms to harden. I have no problems at all if I just put the plane away without running the carb dry.
OTOH, when I tested a Chinese import engine, the carb went bad in a few runs. Certainly old walbro stock diaphragms. Replaced them and saw no more problems.
I do believe, that worldwide the fuel can, and will have more influence on the carb parts than the fuel companies care to admit. I am happy to live in Europe, where good ingredient limits are installed, and low quality fuel is no longer available. Don't blame the 10% ethanol. Your carb is up to that task.
you have to run dry to get the alcohol out of the carb.no alcohol no diaphragm dry out.
the carb can handle the alcohol but it can not handle the moisture the alcohol absorbs and deposits inside it.
seafoam is crap, it is naptha aka coleman fuel 55 octane bilge fluid waiting to detonate your engine apart (if it a high performance two stroke)
Water damage is a bigger issue with alcohol bearing gasoline than diaphragm drying.
I quit using 92/93 octane gas in my small engines as well. The muffler on my snowblower would glow red on high test gas. It doesn't do it on regular 87 octane. Rumor had it that the slow burning gas is still burning when getting blown out the exhaust valve and the muffler glows because of that. I just figured small engines run better on non-ethanol gas... At least for me, they don't.
rumor its just a rumor