how did i lose all compresion?

[XT250]

hey , today i got my spark and all to work but when i tryed to set the timming 7 degrees i dunno what i did cause after it started i had very little throttle control and it stayed revin high , then it shut off then i went to kick it and i had no compression , i think i need new pistion , but how do i get one cause no mail order  has my yamaha xt 250 four stroke 1983??

[jasonm.]

I don't know what you are doing , "adjusting the timing 7 degrees". These are not old big block chevy's from the 60's. There are timing marks that are suppose to be used. "Idle" and "full advance". Sounds like you are still without a manual.