Originally Posted by 
gromit
				
			 
			I have 3 that were purchased in the UK years back (Triumph Trident, taking one out when hot and moving to the next cylinder burnt your fingers).
Useful for setting up the mixture at tickover and balancing the carbs if there is more than one.
Gunsons made a number of Automotive tuning tools like a carb balancer, vacuum gauge etc.
I used to deal with Gunsons Sortex who made high speed sorting machines, same company different division. This would have been in the 80's.
Colin