Last year I got one Cimatti from kid for $50, it was a mistake- everything was broken on this ped, every cable, adjusting screw, brakes, lights etc. I did spend many hours fixing this one. So I don't buy peds from kids anymore- it cost to much to fix them. I don't blame kids- I did same thing when I was in their age.
Start with checking compression and spark.
you'll need at least 120 Psi and good blue spark, if you have good compression and spark check tank, fuel petcock, clean carb.
Read Fred's guide in resource section.