Hi I have a 1988 kx 80 with good compression and a good spark but won't kick in any one help thanks

Do you know if it is getting gas? Is the spark plug correctly sized? Was it running and just quit, or did it run fine, then you shut it down, and then a day or so later it wouldn't start? Need to know more info. Have you tried push starting it? How cold is it in your area. Is the gas mixed correctly? Lots of things it could be. Let me know what you have tried, and I will try to suggest further rememdies.

Check air filter?

What do you mean by, won't kick in? Are you saying kick start won't engage? If so try push starting it. Put it in third or fourth gear, hold in the clutch, have a friend help you push the cycle as fast as you can, and let the clutch go. Let me know what you find. Good luck, and happy riding.

Also check your kill circuit. If the grounding type, disconnect.