they tell you to do that so you can get a socket on the crank bolt to turn motor and get the rocker on the flat spot of the cam so you can adjust valve/ rocker clearance. since you already took the whole cover off just go ahead and do it.
if you want to get that plug removed so you dont have to pull cover off every time heres what you need to do. go to local autozone and get what i believe they call an impact driver. its about an 8" long 2" wide steel cylinder that comes with some large phillips and flathead bits. its about $10 i think. you can set it for left or right so in your case set it for left. put the big flat head bit in there and seat it in slot and turn as if you are trying to loosen it. this will seat it against edges of slot. hold the body of it firmly and strike the top with a
. as the
pushes down it will turn the bit (as long as you are holding body of it tight) this is a great tool and a must have for these bikes. it puts downward and turning pressure on fasteners at same time breaking loose seemingly impossibly stuck fasteners. works on flat and phillips screws and if you remove the black bit holder you will find a 3/8 ratchet head for sockets so you can do the same with any flange head bolt. dont use on non flange head (regular) bolts because the downward force will go to whatever its fastened to possibly breaking things.
Trikes: All Honda: 84 250r, 85 86 and 87 250sx, 84 and 85 125m, 79 82 84 and 85 110's, 73 us 90 and 77 atc90, 75 atc70
Cycles: Honda: 71 cb100, 78 cb750 coming soon cb750 trike. Yamaha: 67 yds 3 (250cc, 2cyl, 2 stroke), 82 750 SECA
Other toys: Chenoweth VW sandrail dune buggy, old race go kart, racing mower, 76 Arctic Cat Pantera 440 snowmobile
KEEP IT ON ALL 3 OR AT LEAST 2 AT A TIME