larger spark plug gap

[fordman]

this is on a lawn mower. B&S i moved the spark plug gap up on three lawn mowers today because they wouldnt idle up fast enough to mow they would bog out and die before you could move them. after cleaning up the carbs on them. they woudl run better but still shooks and seemed to misfire. or soemthing. anyway i gave up and came hme. i looked up the proper gap and narrowed the gap back down 5 from 35-30. and now they seem to run much better. what is the deal with them running so bad with a larger gap on the plug? i figured a larger spark might pep it up a bit.

[Bullitt390]

Lawn mower magnetos just don't produce enough spark for a big gap. what is factory spec... 28 to 32 maybe?

Josh

[fordman]

30

[fireguywtc]

Adding to bullitt390, it could possibly run better with a bigger gap in the plug, but the catch is you need to produce a bigger jucier spark to jump that gap. If the gap is far and the spark is weak, the burn will be inefficient.

[george worley]

Find the throttle lever or govenor spring on the carb. and put a wire on it so you can pull it open before you hit the tall grass.

[fordman]

it was even making it far enough to get into any grass. i regapped all of htem back to 30 and only one seems to have made it good enough to run very good enough to mow. the other two still have fuel /carb problems. i need to dump the gas on the one mower and get a new carb diaphram for the other. its the kind that the carb sits on top of the tank. the other is a gravity feed carb with a float and bowl. i think the tank has junk in it. it runs until you move it. then it trys to die and then finally dies before you can reach the grass.