TG18 older ones used a 25-1 but the later models 50-1.
if on 25-1 it runs badly try a 40-1 mix first.
also look on the fuel cap some times it's written there.
cg
May 2017
Why not do a simple Google search for: "Kawasaki TG18 manual"?
xxx
December 2016
Automatic Answer
While you wait for answers, we may have found some information which could help you.