My dirt bike has been eating up plugs really fast. When we get a new one it will start on 1st kick and run for about 3 days until it fouls. When we get them out, it is covered in oil but we didn't change the mixture. We are using Opti 2 (2 cycle engine oil). I looked on KTM's website and it is suppose to have a 40:1 mix ratio, but I don't thing that is the problem because we have been running it on Opti 2 for quite a while with no problems. The spark plug is an Iridium BR9EIX made by NKG. It could be fuel / air mixture? If so what would the setting be? No one messed with my carb that I know of but might be the problem.