Also try shifting it with the trans in first gear, sometimes the subtrans gets stuck on mine and others that i have ridden, get on it, start it, put it in first gear, then try to shift from reverse to LO, that will usually shift fairly easy but then to get to HI you sometimes have to rock the trike back and forth by putting your feet down on the ground and pushing it front to back. Having it in first gear for some reason releases the binding and will let it pop in when they do this. I know mine used to do it all the darn time, then this last winter i got a plow for mine and started plowing snow all winter, the constant back and forth from reverse to forward when working with the plow seems to have fixed my binding/stuck problem! I guess something was hanging up from not being used much and it finally wore in. The previous owner of my 200ES did say he knew that reverse worked but he just never used it, and i know he wasn't lying by the fact that there was a huge dirt buildup around the subtrans shifter that took washing to get it cleaned out.. LOL
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1984 Honda ATC200ES "Big Red"
1982 ATC200E "Hondie"
1988 TRX300FW "Project Quad" Still in progress....