You can get Seafoam at Canadian Tire, NAPA, etc. Somewhere between $12 - $14 a can. You want the one that says "motor treatment". You can use it in your gas, pour directly into the carbs....even use it in the oil. If you put it in the oil, do it just before your next oil change and ride 100 or so km. You'll have blue smoke behind you when you put it in your oil but it will help to clean out the gunk.
I'm in Kitchener so not that far from you. I have a 2nd Gen and not that familiar with the 1st Gen but there are some people in Burlington, Caledonia, and even a notable person in Brantford that know the 1st Gens intimately. Some more intimately than others.
:-)