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You don't have to remove the shelter JW. I guess you meant the cowl, which does make it a little easier to get to the coolant drain plug.
This is how I did my coolant system flush. With the engine cool remove the right fairing pocket, reach down and remove the radiator cap. Then the 8mm coolant drain bolt above the oil filter.
When the coolant is all drained, I poured some distilled water into the filler neck to wash any crud out. I don't know if that done any good or not, I just wanted to do it. Then the put the 8mm bolt back in.
Now pour in the new coolant. The 1800 takes about 4 quarts. After three and a half quarts, start the engine and let it warm up. Then snap the throttle a few times to burp air out of the system, air will bubble up out of the filler neck. Burping all the air out is what takes most time.
Top off the radiator when all the air is out and replace the cap.