Pending how many miles are on the bike, indirect the sprockets and make sure the teeth aren't wallowed out or hooked. Badly worn sprockets will definitely cause popping and clicking. But may be as simple as an adjustment issue. Excessive side play in the chain can cause noise too.
I believe his autocorrect may have "fixed" High On Octane's post to read "
indirect the sprockets" instead of "
inspect the sprockets", and that is a fine idea. It is probably impossible for someone else to diagnose your clicking without hearing it, but here is how you might be able to do it yourself: Go somewhere quiet, and put the bike up on its center stand--maybe on a board to be able to get the rear wheel up a little higher. Weigh the front end down or have a buddy hold it down so the rear wheel can spin freely. Listen carefully while you spin it, and you may hear the source of the clicking. Check if the alignment of the rear and front wheels is true and straight. A piece of string or a very long
straight bar or length of wood held alongside the wheels by you and your buddy may help you to better determine this. If it is
really off-center you will not need laser-based measuring equipment to see if the rear wheel is askew. This might cause the chain to "tock-tock-tock" off the chainwheel as it travels, especially under greater load.
While you are there staring at your rear wheel, carefully inspect the rear hub's drive sprocket teeth looking for badly worn, chipped or even missing teeth. If its teeth are badly worn and
'hook-shaped", it should be replaced. They are not usually too expensive. Rear drive sprockets usually wear much faster than the smaller typically harder steel drive sprockets at the forward end of the drive chain, driven by the clutch assembly, but if you can examine it easily, perhaps with the help of a iittle mirror and flashlight, now might be a good time to do that. It is usually best practice to replace both drive sprockets and chain at the same time, but you can sometimes get away with just a fresh chain. Still, a badly worn sprocket will greatly accelerate the wear of even a brand new drive chain and vice versa. Now examine the drive chain itself. Does it have uneven up-and-down slack through its run? (Is the slack an inch or so in one spot and much more in another?) Could a roller or three even be missing? Now pull the chain side to side. If the slack side-to-side is more than about the length of a sprocket tooth, it needs to go. When in doubt, replace it. If you can, replace both the chain AND both drive sprockets.
The above will probably solve your clicking problem, but it is also possible you have a bad wheel bearing that is objecting to your bumping along down the road with 3 or 4 riders and the village goat wearing its ceremonial hat aboard. There are three bearings, but most likely it would be the one in the brake drum. You may need to pull it apart anyway to replace the brake drum and final drive gear, but before that, try gripping the tire and moving it side-to-side. If there's a lot of play at the hub you may need to investigate further, or just bring the wheel to a decent Enfield shop for a proper rebuild. Bearings can be a pain in the ass unless you have the right tools.
Good luck!