I have had good success with EBC and White Brothers.
like i said..
i have now a brand new EBC-clutch-kit in my 87 kx250 (exactly the same like kx500 83-2004),
because i smoked it in the last race at 29.june . story: won the start, was leading 2 laps, then i lost the gearlever and tryed to ride the rest of the race in this high gear, that was actually in. so i smoked the clutch and had to quit the race. i could roll the bike with pinned gear back to car.
yesterday i fixed all with new gear lever,good used shift shaft with better splines and new clutch kit. runs like new.