I have a John Deere 400 Lawn tractor with snow blower and blade, when the engine is worked, the engine will almost stall out and spew out black smoke. I have to pull back on the hydrostatic drive to build the RPM's up. Any ideas on what could be wrong?

If its 'black smoke" and not gray. Black usually means a bad ring in the cylinder that's picking up crank case oil and passing it through the rings into the combustion chamber witch could account for the loss in power under load but the motor runs fine with no load on piston and easy strokes in cylinder. Next time it does that can you put your hand by the exhaust and see if its spiting oil. Another to check is pull plugs and see if one is really dirty and that's the culprit. To know for sure do a compression check on all cylinders
Now if its more toward the gray smoke its starving for air under a load. Check for clean air filter. Are their any carb adjustments for air and fuel adjustments?

Signed 21 boat

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Hi,
JD 400 uses a Kohler K532 engine. Replaced the points and condenser recently? The cover is on the top right side of the engine.
Peace,
Clarke

No power nothing no electeric