I had an interesting occurrence. My Twist 60 with the Super Tiger .90 running Gas/Glow was continually being finicky to adjust. When I got a good idle adjustment, it would hesitate on acceleration. When I got it rich enough to transition, the idle was crappy. Finally, since it really was acting like a "too large a carb" problem, I checked the size of the carb I had put on it. I was shocked to see it was a 12.7mm!! WAY big for a 15cc engine!

When I first ran the engine on Gas/Glow, I had problems with the Zama carb diaphragms. Aggravated and in a hurry, I just grabbed a Walbro out of my box of carbs. They are all in plastic bags, marked by the seller with the size. The bag said 11mm, and that's the size of the Zama that was on it, so I mounted it up and adjusted it without double checking the size. It ran better on the test stand because I wasn't slamming the throttle open as fast as the radio (servo) does in the plane.

So realizing my mistake, and the problem, I prepared an 11mm carb to put on it, but I decided to first check the max rpms with the big carb just to see if it would lose any power in the carb swap. I got well over 12000 rpms on an APC 13 x 6. I remembered it was around 11600 with the Zama 11mm carb before the diaphragm gave me trouble. I hated to lose that power, so just for the hell of it I put the glow heat back on. I was easily able to adjust it for max rpms, a nice slow smooth reliable idle, AND a perfect transition. At that point I decided to stay with the huge carb and just install onboard glow heat, which I just finished doing. A 3800 mah battery weighs 2.24 ounces and will fly it for well over an hour with the glow heat on full time, and it runs perfectly.

So, the lesson is, if you are having transition problems that you can't tune out, go to a smaller carb, or try full time, (or even part time; below 1/3 throttle) glow heat. I'm not going to run glow heat on my other Gas/Glow planes as it's not necessary, but it works well in this particular case.

BTW -- The Twist 60 is a rocket with this engine, and a blast to fly!!

AV8TOR