Today I found a performance improvement by accident. I have three bikes with Kings 80cc (70cc) motors. One bike always seems to have more punch than the others and has a higher (louder) pitch. After looking, I found that the only real difference was that the strongest running bike had a "Sparky" spark plug boot and 20 year silicone Accel Yellow Jacket 7mm solid copper core plug wire. I changed to the same setup on another bike and it gained about 2-3 mph with no other modifications. The new plug boot has very low resistance and the stock plug boot has high resistance to help remove unwanted radio frequencies (RF). Many spark plugs and spark plug caps use resistance to remove RF that interferes with TVs. The plug I prefer and use is the Denso W20SF-U.
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