Small Engines (Lawn Mowers, etc.): 17 hp briggs model 31f707, hp briggs, loose power

Question
have a JD L100 42" riding mower with a 17 hp b&s engine model 31f7070 that is spitting back through the carburetor.  it cranks great after adjusting the valves to .005 intake and .006 exhaust.  run fine when it first cranks but within the first minute starts to spitting back and the problem comes and goes.  if i idle it down it seams to run smoother.  the spitting also get worse when i engage the blade and seams to loose power.  any suggestions?  thanks in advance RF

Answer
Hello Ralph, sounds if you have a seal problem or possible some kind of gasket problem. If you are losing power it means that the compression is being lowered; which means it has something to do with air and fuel. Get yourself a note pad and again diagnosis the problems.