I have an LA115 that has recently developed a stumble. By stumble I mean that at all rpms the engine is falling back for a few rotations. At low rpm it is very noticeable. Little tractor has abt 250 hours on it.
The bar that connects to the butterfly at the exit side of the carb is moving in synchrony with the loss of engine power.
Is that function driven by a vacuum line or tensioned by a spring?
Mike, I believe the bar you're talking about is the governor arm and is controlled by engine rpm. Your throttle lever "sets" the governor to a certain engine rpm. If this rpm falls, the governor opens the carb to bring rpm back up. If rpm increases, governor closes carb to bring rpm down. There are springs involved, but I'd look at cleaning the carb first. Also, check vent hole in cap and change fuel filter (if equipt). Bob