The flame on the pilot light on my old Canon Gas Miser fire is too high and leaves black ash. Is it possible to regulate it?

Depends on the age. Some older units have a variable pilot. Look at the gas valve for a small screwed in cap/plug that may say pilot adjust or pil adj, something like that. Carefully remove the cap and you should see a small adjustment screw. Tighten to reduce the flame but make sure to keep it high enough to keep the thermocouple in the flame.