Hi fella, what have you tried,,,, Take a look at the spark plug, is it the right one for the bike, is it gapped correct. Plug lead and cap, are they good, any cracks or signs of arcing, change them. I take it your on points? have they clean contact surfaces (un pitted) if they are pitted change them AND the condensor. Timing? is that correct? adjust by moving the stator plate if needed, you will need a strobe light for this.
Carb problems, air filter?, missing, choked up, blockage in inlet, a rag under seat if a common one. Carb, is it clean, like really clean?, if the bike has been standing petrol varnish builds up and can choke up air ways the emulsifire (check spelling) tube. Float hight set correct, needle clip sitting in centre groove, air bleed screw set somewhere near, wind it all the way in and then wind it 1 and a half turns out.
You will need high pressure air (compresser) to blow all air ways through. Carb removed check rotor valve plate for scoring and damage, replace if needed. Air leaks, check all gasket / O ring seals for condition replace if suspect.
Oil as in two stroke, use quality stuff, you running mixed or posi lube, make sure your oil ratio is correct, too little oil motor runs hot and to much oil motor also runs hot.... Sorry Steve, nothing in any order, just do everything and see how you go, are you a heavy drinker, smoker or drug user,,,