Re: GravelyL1 tractor walk behind
I do believe you have a magneto timing problem.
Hopefully, you have a Wico magneto and can hear the impulse arm 'snap' while hand cranking. And hopefully no previous owner has messed with the lag-angle setting on your magneto.
Remove the spark plug and reconnect the plug wire, ground the metal part of the spark plug, or just ground the plug wire while making the following adjustment.
If the nut on the magneto adjusting block is visible, you are on the compression stroke, nut down is the exhaust stroke. The magneto turns at one half engine speed, spark every second time the piston comes up.
Now you need to find the high point of piston travel on compression, TDC. Place a long thin wooden dowel down in the spark plug hole and follow the piston travel. Mark the high point of travel, TDC.
Now while you hand crank, don't even look at the back of the magneto, listen for the snap. The snap should occur at TDC, or TDC plus a tich. Adjust the block until you get the snap at TDC + a tich. While hand cranking you want the spark to occur just before the piston starts heading back down after compression.
Spark before TDC can cause backfires and starter straps being ripped out of hands.
Spark well past TDC may be your problem, ignition with the exhaust starting to open.
Faux Pas are my forte