KTM 250SX
Last race day I experienced bad detonation from mid range up after about 2 laps of racing. Was a nice autumn day not too hot.
Track is deep sand/loam, bike does work hard, but has never happened before.
Fitted it's first set of new rings before race.
Jetting is standard, except needle is set on leanest clip and main is 2 steps richer.
I don't think I have a air leak as runs great up until a few laps into moto, then sounds like ball bearings in a tin can. Pull over, revs out in netural no prob , take off again, then after 1/2 lap under load it comes back.
98 octane fuel r30 @ 50:1
Any thoughts ?