The 200ES motor removal is a PITA!!! I have done it about a dozen times now, twice on mine, long story, and at least ten others that i have pulled to rebuild the top end on.
You can actually remove and reinstall the motor without having to do anything with the rear end, takes a little practice but i can now get one out in about a half hour, maybe less if i really wanted to hurry. The key to it is taking it out the right side and taking the right stuff off. I generally pull the exhaust off the head and remove the pipe at the muffler, then disconnect fuel and remove carb, disconnect electrical, remove the shifter, and the last bit is slide that rubber boot back on the driveshaft tube at the motor end, the only thing holding the driveshaft to the motor is the spring pressure holding the splined universal joint to the output shaft and the boot connecting between the two. Once thats done remove all the motor mounting bolts and bracketry and lean her out to the right side and out she comes. Getting it back in however is the challenge but after doing it a few times i found a way to do that as well without any rear end teardown, i put the ass of her up on jackstands, rotate and slide the motor back in again from the right side then line up the driveshaft and rotate the back tires to spin the shaft, after a few turns it seats in and you can push the motor back to compress the spring and slide in one of the motor mount bolts, from that point on its just bolting everything back up.
I have yet to pull a rear end on a 200ES to get the motor out, sure its a little more work to get it back in, but its so much less wrenching on it as a whole! Good luck on the rebuild!
Oh one last comment... The Champion plugs have always been total crapola for me, they generally foul and die in less than a week of average use. The NGK in there now has about 8 months on it, hasn't fouled yet, but then i did a full top end rebuild and new carb so she's tuned up pretty good. But make sure you check your exhaust!! Believe it or not i fought mine fouling plugs and running like crap for about 3 months, turned out the rotted interior of the muffler was causing flow problems for the exhaust, swapped out the exhaust for a newer free flowing bolt on replacement and cleared up the fouling.
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1984 Honda ATC200ES "Big Red"
1982 ATC200E "Hondie"
1988 TRX300FW "Project Quad" Still in progress....