I did a search on this issue didn't see it discussed. We have encountered a pattern with four different 250 sx bike 2012-2013 bikes,all four of the riders complained about difficulty shifting from 2nd to 3rd while under heavy acceleration. (could not be duplicated under lesser acceleration attempts) (shift problem usually occurred while pulling hard out of a corner) Eventually the riders couldn't shifting from 2nd to 3rd until repairs were made, with a little research I found some information on this issue but little on the cause or suggested fix. Our local Colorado speed shop LSE (Leavitt Speed Equipment http://lseracing.com/) developed a repair that has successfully fixed this issue on all four bike. It included polishing the SHIFT DRUM and replacing the wheel on the LOCATING LEVER with an actual bearing. I guess my question is has anyone else encountered this problem is this a prevalent problem or an isolated issue?