LT1000 Lawn Tractor - surging

[oldnslo]

If this model has manual choke can you slowly apply the choke to see if the engine will run smooth? If yes this would also point towards a fuel air mix issue AKA partially blocked jet.

 

[Thomas]

Vent hole clear?

 

[tomplum]

I would guess that you have hit the nail on the head. On several occasions I have had to use a small nail or hand held drill to open non-adjustable main jets. You do have to be careful not to make it too big. You may have to do several adjustments to get rid of the surging.

High engine speed fuel mixture is mainly controlled by the main jet, idle mixture on the other hand is mostly from the idle jet.

Richard

It helps to think of these differently. The carb while operating without a load relies on the low speed circuit. When you look at a clean carb and wonder why it surges with the main spotless, this tends to be the answer. Next one of these you have, fiddle with the low speed and the surge will improve if not go away completely.