Hi RD
I will have to remain off the fence on that one I'm afraid. I know with other 2 strokes I have built and run they have been very particular about plug choice and I would never think about leaving the thread protruding that much into the combustion area. From what I remember about the combustion area design the size of the squish area and the dome are so critical to flame speed and direction that having the spark so far from the optimum distance is encouraging pre-ignition, an easy thing with coke build up. Also the heat rating the plug will be seriuosly affected as the threads direct interface to the head is considered when assigning the plug it's heat rating.
Getting A Head
I have heard that angling the gap toward the inlet ports by the use of plug washers/shims (which one in the case of the pocket bike multi-port inlet is anyone's guess) "could" be of some benefit but even that is subjective, I don't think there is any hard evidence to support it.
Dylan
