Double over the braid were it is clamped. Check often.
OR drill and tap a hole in a fin and bolt on a ring terminal on the ground.
CH also has a billett machined cap similar to the one on the BME 110 but its for a 14mm plug.
A correctly operating CH ignition will fire a .1 plug gap in the open air. Open up the gap on some old plugs and see what kind of spark you have.