I’m usually pretty good adjusting my engines; but I’m having a problem with a new gasoline engine that has me stymied. Now this engine is new and only has about a gallon of fuel through it. It’s a small, 25cc Roto with a Walbro carb.

The engine runs well enough both in the air and on the ground except for the two problems related below. I am currently running the engine on a 32:1 mix, sea level, moderate, to cool temperatures.

I have tried adjusting both the low and high needles substantially. Going substantially rich or lean does not seem to help. I’m just wondering if I have to run this engine more before it will start to settle down. I do let the engine warm up before I set idle or fly it.

Problem #1: The plane lands, at the end of a flight, with a much higher idle than it started with (guess that’s better than a lower idle [] ).

Problem #2: If I move the throttle quickly from idle to open the engine will hesitate or die unless I catch it by reducing the throttle. It does not do this going from wide open to idle quickly.