i raced my gotech 21 7 port for the first time today. after run in i changed the plug, checked internals, all ok . problem was i didnt make 7 mins first heat, was still on the rich side. i leaned the top end a bit to just be making 7 mins, was still a bit rich. i find that there was a very fine limit of tuned on the rich side, to being too lean. i blew a plug after 6 in mark, came in and i still had half a tank. this was leaning the top end 1/8th of a turn. so i richened it back up , and struggled to make run time. ill measure where the needles are at tomorrow, see if im in the general area.
when tuned on the rich side, it had good top end but lacked a bit on the bottom. im using the std restrictor that came with the engine, how ever i do have 4 different sizes to try. thanks.