ok little back story my brother bought this bike to ride with me, his first time out he is keeping up very well in flats and turns then we hit some hills and he did not know the trail and launched himself in the air when he hit the ground broke both of his leg so myself and a friend fix up the bike so he can ride it everything runs perfect then my friend and i decide to race to see whose yz is faster mine is a 1991 with everything that could be possible done with out a big bore and he is on the 96 yz250 in all of his wisdom he just holds the throttle wide open for i have no idea how long and then the bikes dies has no compression and wont start now lets fast forward about 2 years to now. my had decided he wanted to buy the broken bike and i told him i would rebuild it for him, the rebuild was a success i had gone through the whole top end all the bottom was fine just fried the rings and piston. the bike fires up how it should but the power valve will not open to i removed it and it is all clean everything moves with ease so i pulled the cover for the linkage and started the bike revved it and the arm for the linkage is not moving but still has tension when pulled on. i dont know what to do or where to start any information would me amazing and thank you in advance!!!!! P.S. i know my spelling and grammar are terrible.