The type of engine you have (ABC or ABN) is designed so that the pistion and sleeve are very tight when cold and the sleeve expands somewhat when the engine is running from the heat. Running it too rich which will keep the temperature down can cause execessive wear on the sleeve which when run at the proper temperture will result in a loss of compression which will be noticed as loss of power. You could also damage the chrome or nickle liner plated to the sleeve. Read the instructions and follow them or have someone with experience help you.