My 110 is like this. The front sprocket is under the left sidecase. The High-Low range box is an easy removable assembly of 3 or 4 gears (can't remember exactly) Anyway, after that comes off you take the gear lever, pullstart, and flywheel off, then remove the left sidecase and now you can change the sprocket. You DO NOT have to take the whole motor apart!!
Justin ~hondaATCman~
'82 Honda ATC 110
'81 Honda ATC 250r (Summer Project)
'87 Suzuki LT 250r Quadracer - Very Modded...FAST!!
'03 Yamaha Big Bear 400 4x4
'85 Ford Bronco II 4x4 2.8 V6