Cut loquat fruit in halves, and remove the seeds from each one. Do this until you have about 4 packed cups of loquat fruit halves.
Dump the cut loquat halves into a large pot.
Add enough water to the pot to cover the loquat.
Next, cook the pot over medium heat and cook covered for about 30 minutes until the fruit softens.
Use a potato masher to mash the fruit to help remove the juices from the skin.
While the fruit is cooking, fill the canner about halfway with hot water. Place it on a burner with the lid on and bring to a boil.
When the water in the canner is boiling, you can add the canning jars to the jar rack inside the canner to help sterilize the clean jars with steam while the fruit is cooking. Leave the jars on the rack OUT of the water, do not lower them down into the water at this time.
Place the jar lids and rings in a small pot of water, and heat over low heat on the stove, do not bring to a boil.
After the fruit has been mashed and cooked, remove from heat, and strain it using some cheesecloth or a fine sieve. Press down gently on the fruit to squeeze out some of the extra liquid while straining. It is hot, so you may need to use a back of a spoon to press.
Measure out 4 cups of the fruit liquid. If you do not have a full 4 cups, you can cook down additional fruit, or add just a bit of water to get to the full 4 cups of liquid needed. If you need more than ½ of a cup do not add water for additional liquid. In that case, you would need to cook down additional fruit. If you don't you will end up with watered down taste to your jelly.
Mix ¼ of a cup of sugar with a packet of Sure-Jell pectin in a bowl.
Add the 4 cups of loquat liquid back into the large pot, and put it on the stove on medium-high heat. Add in the pectin/sugar mixture, and stir or whisk well until combined.
Bring that pectin/juice mixture to a rolling boil. You want the mixture to form a boil that cannot be stirred away. Be sure to stir often to avoid any scorching or burning.
Now add the remaining 4 cups of sugar, and stir well to combine.
Bring the mixture back to a boil, and continue boiling for 1 minute.
Remove mixture from heat.
Use a jar lifter to remove the sanitized canning jars from the water bath canner rack. Fill each jar with the jelly mixture making sure to leave about ¼ of an inch from the top.
Crab the lids from the hot water with a magnetic lid lifter, and place them onto each of the filled canning jars.
Now put the rings onto the canning jars over top of the lids.
Use the jar lifter to place the canning jars evenly into the rack in the water bath canner.
Carefully lower the jar rack into the boiling water in the water bath canner. Process them for 5 minutes.
After the 5 minutes, lift the jar rack out of the boiling water in the canner. Using the jar lifter to remove the jars. Place the jars on the counter on a towel, and wait for the lids to make a popping sound.
This process can take up to 30 minutes. You will notice that the buttons in the center of the top of the lids will push in when this sound occurs, indicating that a correct seal has been achieved.
If at the end of 30 minutes, you notice the buttons on some jars have not popped down, you will need to place the jars that have not sealed back into the water bath canner to process for another 5 minutes.
Leave the jars on the counter to cool completely before storing.