hobbico red after run.
never had an issue with any other motor. ( i have had one come loose before, but was using novarossi after run)

well the real reason why i ask, haha sorry guys, i have a std flash 21 i have to do some work on. now the tuned version matches the crank hole nicely with the carb opening. but the std flash you see 2 mm or more of the crank towards the front bearing side. i want to remove the silicone and reshape the opening to match. then refill the hole. im trying out some red permatex hi temp RTV now, but i will see if i can get the right stuff. cheers.