89 KDX powervalve turns on and off while riding

The powervalve worked when I started the bike. It then failed to opreate after 10 min of riding. I pulled the boot back and saw that the lever was still working, pulling the powervalve out when it should at high rpm. I turned the bike off and was sick to my stomach because I did a rebuild 2 months ago. I started the bike and it worked again. I know when it works or not because the powervalve gives that high pitch scream. I rode it hard for about an hour afterwards and it seemed to work well, no sticking. Then coming back home it failed to operate correctly. The powervalve just works when it wants to. Im running a 50:1 mobil 2T and it does smoke a little. jets are 48 pilot 152 main 1173 needle. the valves and gears are new from fredette. What could be the problem? THANKS

The bike powervalve opens at a higher rpm, and when I rode it during those times it felt and sounded like a loud fart. It may have been stuck open? It felt dead

50:1 because the valves got too gummed up at 32:1

took off headpipe and saw that the let valve was broken in half. the valve itself moves freely i dont know why it broke. how do i take out the middle valve?