I don't think anything major was modified from stock. It has an after market tail pipe, I put a Tusk clutch in it, and it has a 13/54 (I think) sprocket ratio -- geared for trails.
I didn't adjust the mixture, but it's a 4-stroke, there's no rich/lean adjustment to do... is there?
I ride around the neighborhood and on trails. I noticed the loss of power, stalling, backfiring when riding trails, and when taking an Experienced Rider Course (all riding drills in a parking lot on a hot day in 1st and 2nd gear) at the local community college.
Thanks for your help!