Hello, I am having a problem with my 2007 250 XC (used for motocross) blowing pipe o-rings. I have searched online to no avail, and have inspected the flange for wear, and it looked ok. I feel as if it may be running hot, but jetting seems OK. For a while I have been noticing pipe bang after about 10 laps on a new set of o rings. When I take the pipe off, the o rings are rock hard, and both are broken on the left side. Using FMF o-rings that came with the pipe. Any ideas? I am stumped and would appreciate any input.