Hi Oldguy,
This sounds like the engine is what is called “fourstroking” and is caused when the carburettor mixture is too rich at that particular throttle setting. This is how a two stroke’s mixture is adjusted. If the engine “fourstrokes” at any particular throttle opening it needs to be weakened gradually at this point whether it be cut away or needle etc. until it starts to “twostroke” smoothly. You soon get the feel of it and know when the engine is happy. If you suspect it is weak at a certain throttle opening, you can richen it at that point then gradually weaken it off until it runs smoothly without missing.The fuel level in the float chamber also has an effect here. A two stroke doesn’t need extra fuel to keep cool, it is the correct mixture or nothing.
This was not a silly question!
Regards,
Bob Mather.
