take the gold engine...put a 8 mm insert in the carb... drop out 0.2 mm head shim..basically take out the brass shim and leave the 2 aluminum shims.. grab a #6 or #7 glowplug..... add a 9886/41001 or a 9853/41001 and you will have a monster of a engine that will run like a raped ape !!!!