Airplane engines operate at full throttle and a very high load on every take off and climb. Then in cruise about 70%-90% full throttle and load. Cruise power is normally set by leaning the fuel mixture to achieve a desired cylinder head temperature. The lead prevents detonation in all of those situations. Decent, landing, taxi and idle are pretty much just idling with no heat being generated inside the air cooled engine. If the pilot doesn’t lean out the fuel mixture after landing or any time when idling. The bottom spark plugs will and do foul during normal operation.
I am a member of a flying club. I have found it common to get in a plane flown by others who obviously don’t lean on idle and have misfires. Piston powered planes have two seperate magnetos with two seperate plug wires and plugs. That is done for redundancy. A normal preflight run up is to let the engine warm up while taxiing to the take off end of a runway. Rev to 1700 rpms and turn off each ignition system. The rpm should drop no more than 50 rpms. The club planes drop more than 50 about half the time. When that happens I just lean the mixture until it heats up enough to burn the lead off the plugs and the rpm’s climb back up to at least 1650 and all is smooth. Sometimes the plugs are too fouled and I don’t get to fly that day.
So, back to the original question. Lawnmower, go for it. Anything air cooled and run wide open with a load will be fine. Liquid cooled, mixing should be ok but 100% might cause fouling of the plugs.
I also can’t run it in my multifuel M35A2. A big data plate on the dash says NO. I put some in to thin out the used motor oil one time by accident with no issues. But apparently running 100% a gas will cause a pretty blue flame out the stack which could cause issues for anything or anyone in the back. I’d love to see someone else do it though.
Crews and worthy rigs Around the country
