I looked online at several recipes for mixing your own sports drink and finally settled on one that has worked out pretty good.

The recipe for a four hour bottle is:

3.0 cups of water
2.0 cups of maltodextrin (1000 calories)
3/4 scoop GNC chocolate flavored whey protein (100 calories)
6 capsules of Hammer Endurolyte Extreme 

Bring the 3 cups of water to almost a simmer. 
Pull the 6 endurolyte capsules apart and empty the contents into the water.
Put the scoop of chocolate whey protein into the water.
Slowly stir in the 2 cups of maltodextrin making sure it fully dissolves.
Once fully dissolved pour into a 26 oz water bottle.

Do this the night before the ride and put in the refrigerator overnight so it will be cold the day of the ride.

Drink 1/4 of the bottle every hour on the hour.
This will give you about 275 calories per hour and the necessary endurolytes.
You will need to drink at least 8 oz of water when you drink the 1/4 bottle, otherwise the osmolality of the maltodextrin is too high for your stomach.

It turns out that there are a couple of non-obvious things involved when mixing up the drink.

The total time to make the mix is about 5 minutes.

Use your water bottle to measure the amount of water required.

Fill the water bottle you are going to use up to an inch from the top with water. All of the other ingredients are going to dissolve in the water and hence not add any volume to the mix. You want to leave an inch of space at the top of the bottle so that you can shake the bottle contents easily when you are done.

Pore the water into a pan an place on high heat.

While the water is heating gather your ingredients together.

Pull the capsules apart over the heating water and let the capsule contents empty into the pan. The instructions I found on-line said 4 capsules but I sweat a lot so I’m using 6 capsules in my mix.

Now add about a scoop of whey protein. The measuring scoop comes with the whey protein and is usually just resting on the top of the whey when you first open the whey container.

Once the water starts coming to a simmer you can add the maltodextrin. You will need a whisk to constantly stir the water while adding the maltodextrin. I add 1/2 a cup at a time while stirring. Wait for the 1/2 cup to dissolve before adding another 1/2 cup. I use 2 cups total of maltodextrin.

Once the mixture is fully dissolved (you may have some small chunks of protein) pore the mixture into the bottle. Make sure the top is fully closed and then shake the bottle pretty good. Before putting the bottle in the refrigerator you will need to open the top. If you forget to open the top before putting the bottle in the refrigerator then in the morning the bottle will be crushed because the hot expanded mixture will shrink while it cools and collapse the bottle because air cannot get in through the top.

Probably the hardest part of all of this is remembering to make the mixture the day before so that it will be cold the day of the ride.

Interestingly enough when I ordered the Hammer capsules they also sent me a bunch of samples of their other stuff.

One thing was their Hammer Recoverite Drink.

Looking at the back of the package it has the exact same ingredients used in my sports drink.

The difference is that the Hammer Recoverite costs $3.25 per package and the equivalent amount of my sports drink costs $0.13 cents.