[MattR]

I hope you don't mind me moving this thread. It was out of place in the Riding Techniques section. I decided to put it here in the Enduro Technical forums but then couldn't decide if it was Engine or Other... oh well, it is now in Other.

Back to your topic...
I have an Excel spreadsheet that I use to do any combination of oil ratio and gas quantity. It prints out a nice table in increments of 0.25 gallons of gas. If you (or others) want it, I can email it to you. However, you did the math correctly so you probably don't need it now.

By the way, I like to use 40:1 premix which is about 10 oz. oil with 3 gallons gas. You can use a small juice bottle that is 10 oz. to store your oil during a bike trip. Then, fill up at the pump and pour in your desired amount depending upon the gas quantity (1 gallon gets 1/3 of the juice bottle, etc... or put markings on the side for more accuracy).