Hi remery and Norm,
Probably a few things that need checking.
Adjust Mixture Screw: Start by slightly adjusting the mixture screw on the carburetor. Typically, turning them clockwise leans the mixture and counterclockwise enriches it. Make small adjustments and observe the change in throttle response.
Check Main Jet Size: If you have access to the original specifications for the main jet, ensure it is the right size. An incorrectly sized jet can contribute to rough running.
Inspect the Needle: Make sure the needle and seat in the carburetor are clean and functioning correctly; they can cause rich running if they are not sealing properly.
Adjust float level to correct specification.
Ensure the ignition timing is correct. If itβs off, it can lead to poor running characteristics, especially under load.
A weak spark can cause rough running.
You might want to inspect the ignition components:
A weak governor spring can cause instability in throttle response
Cheers
Max.
