so I rode my blaster in a parade for 45 minutes revved it a couple of times but that was all then I brought it home and let it sit for the weekend on monday I started it up and it ran fine with it idling and me blipping the throttle, then I put it into gear and started to drive it around just putting around and then the top of the piston hit the spark plug, i was very confused because for the parade it ran perfect so I took out the spark plug re gapped it and tried the same process again and it did the same thing so I am very confused on what the problem could be im maybe thinking its a crank bearing but im not sure. if you all could help that would be great thank you.