Originally Posted by
windellmc
I ran my first JPX with stock head shimming and 30% fuel until I found evidence of detonation. After that I added a shim and also added one to my second engine before break in. I am starting to think the stock plug is pretty cold. It is too bad there is no good way to measure the heat range between different brands of plugs.
actually there is a way to check the plugs....the diam of the hole and the thickness of the wire....its hard to tell and you need every plug in front of you to make the decipher but it Is possible to tell which plug is what if you take the time and look CLOSELY.
