I did a compression check which was 31 psi. It should be 71 according to manual. It did run a few times for about 12 seconds and ran really rough with exhaust gasses coming out of the muffler and also out of the carburetor where the air filter is located (never seen that before). I checked online and in the Honda shop manual it stated that for low compression: check to see if valve clearance is correct, check for excessive carbon buildup in combustion chamber, check for defective valve or valve seats, and check for worn piston rings, piston, or cylinder. Can anyone suggest what I can do to fix this problem? Many thanks in advance for your help.