Hmmm,tough one...first try some carb cleaner down the air intake,check the fuel lines are not squashed or blocked, check you have a spark, check your fuel & oil mix-not too much oil. You could remove, strip and clean the carb because it could be a faulty diaphram but as a last resort, screw the carb adjustment screws all the wayin, make a note of how many turns they each took, and pull the engine over. NO life? turn the screws out half a turn each and pull it over again. Keep doin this until it runs sweet. NOTE-one screw may require more turns to get the engine running smoothly !
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