I have the XYZ 26cc A-Spec.
the engine ran flawlessly for over 4 gallons.
at the beginning, the engine refused to work properly, after further investigation i found that the hall sensor connector was broke, i changed it to a standart JST(futaba, but it doesnt really matter) and it never stopped since...
some numbers, these were taken after approx. 3 gallons of gas running 1:33-40 synthetic (mobile racing), static measurments:
16X8 MA (worst prop ever) - 7700 rpm
17X6APC - 8100rpm
18X6W 7000rpm (this prop loads the engine ro much, you can actually hear the RPM loss at verticals) great static thrust.
16X6APC 8800 rpm

this engine is not a "super power house", but it sure worth every dollar is spent on it.
once you go gas, you never go glow again.