Say, just for extra info, I have done some research and found out that the number on the del jet is in mm. If you have a #80 del jet it is that the number divided buy 100, so it would be .8mm and #100 jet would be 1.00mm. I looked at the drilling jet chart and it can't be correct for what people are coming up with for the jet sizes. I have been drilling jets to find the one close to the real one I need to save money. To make this clearer I wanted to start with a #80 for tuning so I did calculations with my numbered bits. I started with a number bit of 66 and this is .033 inches. I multiplied this number by 2.54 to get cm. I get .0838 cm. Multiply by 10 and to get .838mm so this is a 83 or almost a 84 del jet number. Maybe everybody know this but I thought I would post my findings.