Originally Posted by
dan_vector
Gray wire in the plug is definitely a lean engine. Change the plug before you run it again as once the element is gray it's now brittle and so could break and damage the piston/sleeve/button!
At 240degrees its critical. Depending on what % of nitro, lack of lubrication. No wonder you have flat spotting on acceleration. Flat spotting or bog
down during acceleration causes for the engine to run leaner for a split second, or starve the engine. At 220-240degree we know how lean you are. Remember, less fuel in the tank the leaner the engine runs. If you're actually racing rich to lean every 9-10 minutes, you'll find the balance of it. Being fast is nice, but being consistent is better.