PBI or Sprocket Specialties will make any size you want (Google, both have web sites). $20-$45 depending on tooth count. I had a Sprocket Specialties 49 on my 110 for a while, worked great but I am a bigger guy. I have a PBI on my 200X (Yet to be run) it was $20. With that small of a motor you need to factor in rider weight.
85 ATC110 - The Greatest ATC of all time - (My First - new in 85)
83 FL250 - Odyssey w/420cc - SOLD
82 185s -10.25:1 piston, Full 200x upper, Goki Electric start - SOLD
84 200x - Auto-X - Weisco Hi-comp, Cam'd, Bassani'd, Westcoast swinger, -SOLD
82 200E Big Red -SOLD
85 ATC250ES Big Red - Snow Plow !