Oops need to divide by 5. So fixated on the US gallon to liter ratio I forgot the 5 gallon. Well if you happen to follow a green Versys near Owen Sound that looks like a 2 stroke exhaust--- just meThe perfect mixture is "Follow the mixture ratio to the letter. 1 oz per 5 US gallons of gas."
That is 1 oz per 22.7304 liters (0.924 oz for 21 liters)... As you refill a nearly empty tank by adding 15 liters of gasoline, you'll need 2/3 oz of TC-W3 to maintain the proper mixture.