I ride Denso VW16 Tough. Gap - original 1,1 mm. No probs yet

 

U grooves if I can find them, or autolite. Currently have autolite.

 

it really depends on the quality of the ignition coil - accell 45,000 volt and the dyna 40,000 .040 works well -

compufire 80,000 volt coil we use a machine for Testing with Sun Oscilloscope to determin the rate of energy loss at high RPMs ( dyno pulling ) and gap at that spot to take full advantage of the spark intensity Live --

 

Nice. I've got a Dyna 2000 ignition, but the regular Harley coil. Think .040 is good?

 

the harley coil is really very good - i have only swapped them out seeing cracks in them while doing a top end -- we have a milk crate full of them its a freebe perk for a job