well, if you cant seem to find a solution to your problem, i believe that their is 2 possible problems. i believe that either you have an air leak, or your carb is a little gummed up. i had an engine that was running at 340 degrees at 6 turns out on the high speed needle, and it was just a gummed up carb. i took it apart, cleaned it out with gum out, and problem solved, back to running at 230 degrees. if you have an air leak it is probably in 1 of three places, the carb neck, the backplate, or your front bearing. i dont see why the sealing would void your warrenty, but the life time engine replacement program is where you take your old engine into your hobby shop and give it to them, and they give you some money off of a new engine. i've sealed several motors and used them as trade in and had no problems, ask your lhs if they will still take it as a trade. but the sealing is simple, only takes a few minutes. but if you just want a new one, you'll get like $25 off of a new motor if you trade that one in.