As a rule of thumb when I worked on the Council most mowers /strimmers and the like ran with gaps of a round 20-25 thousandth of an inch try opening the gap and with the plug againstthe engine metal pull it over and you should be able to see if it's sparking. I would guess that your gap is too small but even if the gap was too large you should still see something at 20-25tho unless the plugs the problem of course. Hope this helps
Gaz
Gaz, March 2010
