Before I started using Opti-2, my spark plug was a nice tan color. After running Opti-2 in my tank (100:1) my plug turned light grey. To add another layer of complexity, I have also increased my fuel flow and the plug chop (on a new plug) still shows a light grey color. I'd sure like to increase my jet size until my spark plug starts showing a nice caramel color again (so that I know I have the right size jet for my present fuel/air ratio combustion charge), but is this possible with Opti-2, or is your plug always a grey color with Opti-2, no matter what size jet you're running?
I know that on 4-stroke motorcycle engines you can jet your carb to achieve that same caramel color (even though there is no oil being mixed with gas and hence no burned, black oil residue deposits on the plug)
I know that on 4-stroke motorcycle engines you can jet your carb to achieve that same caramel color (even though there is no oil being mixed with gas and hence no burned, black oil residue deposits on the plug)