What's the valve gap set on a yard machine 139 ohv mtd push mower

A couple possible problem to look at. First your valve gap setting if OHV engine. Too much of a gap will cause the decompresser not to work causing hard starting. Second would be carburetor problems. Easy to check for by adding a little fuel into it throat. It starts and dies then the carburetor is the problem otherwise it can be ignition related.

get down and look at the carb. a little screw on top will allow you to adjust the idle, but;, check the choke, it is stuck in place or mal functuning maybe, but turning the screw right or left will set idle

sounds like the needle valve in the carb is not seating replace them and the oil

primer button is on the front of the mower


Performance Chip

Most all is .0030 thousands. Your owner's manual will tell you.

was gas left in it for more than 30days?if so the carb might need a cleaning

The spark plug is at the end of the thick black wire in the middle of the front of the engine or looking at the mower from the front, it is to the left of center. Make sure you set the spark plug gap before installing it new. The gap is probably around .030". They have tools for doing this at the auto parts store. Sometimes and older plug can be cleaned with a stiff wire brush and some solvent and gapped properly and continue to work well.

0.028 " to 0.030"

but if unit is briggs intek ohv use 0.020 " gap

cheers paul46

It should be under a rubber boot between the valve cover *(stamped OHV or OHC) and the muffler.

Good luck and be careful. Dont pull that boot when the engine is hot!

If your mower does not have "OHV", overhead valves. You can use a Champion j19lm spark plug.
If you discover you do have overhead valves; A Champion RC12YC, will work.