it was running fine after the crash with stock muffler and 14x8... then I switched to 12x8 with rossi ultra thrust muffler... then you guys said it might have overspeeded or something like that cause fuel wasn't getting burnt fast enough so it causes to rich condition hence puffing... today I swapped to stock muffler again with 13x8 prop and I cant go more than half throttle and engine dies... I turned open the HSN 4 turns to make sure its getting enough fuel... and started leaning from there... but didn't work engine still dies beyond half throttle...