What to do if engine exhaust has some black smoke

EM Iowa · Aug 4, 2013

There is some black in the exhaust of my F-20 while idling and putting around. It's not a lot, but could it foul the plugs and make the engine not run well? Which screw controls this ( one on top of carb or near the bottom)?
I'm pretty sure it goes away when under a load, so maybe this is how it should be set up.

David G · Aug 4, 2013

It is too rich, need to lean the mixture.

El Toro · Aug 4, 2013

Do as David suggested and close that main jet screw as this will lean the engine. My Toro mower and Ward's tractor have that feature. Hal

Old-F20 · Aug 4, 2013

if it smokes a little bit at idle but not when your throttled up....LEAVE IT ALONE! its set where it should be

those old zeniths don't have much leeway for adjustments and the last thing you want to do is run it lean while at higher RPMs working it......it'll get hot

GordoSD · Aug 4, 2013

Is that an M carb?

D beatty · Aug 4, 2013

I think if you look at it close I think its off a Briggs & stratton engine.

El Toro · Aug 4, 2013

Its off a B&S engine. Hal

Tom Fleming · Aug 5, 2013

OldF20 is spot on. Rich carb setting is best on these old girls, and I don't mean to the point that idle looks like a diesel with the pump turned up either. But a little black smoke at idle is not a crisis.

If the exhaust clears up at full throttle and working, leave it be, it is fine.

What to do if engine exhaust has some black smoke

EM Iowa

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David G

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El Toro

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Old-F20

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GordoSD

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D beatty

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El Toro

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Tom Fleming

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