I have several more flights on my OS 15 gas/glow engine now and have had excellent results and performance. However, I have had to lean down the low speed needle a bit to prevent the engine from loading up at idle. Also, I have found that the needle settings on both the high and low range are quite sensitive. One has to take their time and be patient about setting the needles.
Best wishes and good safe flying.
Heli-NuBee (AKA Roger the radial rabbit)