Small Engines (Lawn Mowers, etc.): Tecumseh snowblower exhaust valve not closing, engine shaft, key way

Question
Tecumseh snowblower engine. Model #hmsk80 155545t (H). Problem is the engine will start but will only run with choke on. runs at high rpm, and the exhaust gets red hot. I have removed the head, and see no visable problems. Valves are opening and closing.  I have replaced the carb. Also has some backfiring on decelleration. i hope i have given u enough info. Its either hi rpm or it wants to die.

Answer
Brad

Have you checked the timing? Look at the the flywheel key way on the engine shaft,if that was somehow moved or sheared it needs to be in line with the flywheel  key way and the shaft spline.sounds like the carburetor . the reason it only runs on choke is cloged.the muffler is red hot from too much fuel not enough air.also you can bend a valve if engine runs too hot!!!!