Wish I'd gotten to this thread sooner.

You don't need to sell that engine. There is nothing wrong with it. It's a perfectly fine engine that's user friendly and simple to use.

The problems you are having could happen to any engine, and they are twofold:

1. You have an AIR LEAK in your fuel system. There should be absolutely, positively no bubbles, period. The bubbles are keeping the engine from getting enough fuel, and it's dying from fuel starvation in the air.

2. You need to work on the tuning a little bit.

Remove and disassemble your fuel tank and lines. Throw away ALL the tubing. Make sure there are no sharp burrs on any of the nipples or brass tubes there may be in the fuel tank. Buy all new fuel tubing and reassemble the fuel tank. That should cure the problem.

Tuning the engine should be very simple with the airbleed carburetor. The airbleed adujstment has virtually no effect on the engine, and normally does not need to be adjusted. Simply set the top needle, and forget it. Tune the engine for peak RPM at full throttle, then back off 3-4 clicks. At full throttle, point the airplanes nose in the air and listen. If the engine speeds up a lot, it's too rich. You can close the needle valve 1 click and try again. If the engine sags, open the needle valve one click and try again.