Plug gap should be .025"
http://store.chainsawr.com/
.025" spark plug gap http://store.chainsawr.com/
My 16" Craftsman 36 cc chainsaw manual calls out for a Champion RCJ7Y....if that is the same size chainsaw as yours, I would go with that plug.
Depending on the model there should be a cover above the throttle handle. The spark plug should be under that cover.
.025
0.65mm
The correct spark plug for a Stihl 024 is an RCJ6Y (Champion), BPMR7A (NGK), or a WSR6F (Bosch). Make sure that the gap is set to 0.020 inches.
I think it is 0.030".
Champion DJ7Y (gap of 0.025")
Impossible to answer, depends on what model KTM you have.
The correct spark plug for this model is the NGK B-7ES.
0.75mm
Champion DJ7Y. Not sure of the plug gap though.