Just sticking from sitting i'm sure. My 200ES was the same way when i got it, i soaked around the back side of the lever with some PB Blaster then down around the shaft of the shifter, the part you pull up on to change positions. You can also remove the nut that it slides through and squirt some lube around in there as well. With some use it will loosen up. The other problem i generally have is it won't always shift unless its running and in first gear, sitting still just idling in first, then it will shift back and forth with ease.
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1984 Honda ATC200ES "Big Red"
1982 ATC200E "Hondie"
1988 TRX300FW "Project Quad" Still in progress....