This started with a question from Morris on how to adjust his OHV’s valves. My answer is:


First look up the clearance and go over to your local auto parts store and ask for a go feeler gage that covers that size. (It’s .10 mm) By the way make sure is narrow and bendable as some are not. I prefer go-no go types for beginners but you would have to get one from a tool truck or professional store. You will need valve cover gaskets and sealer and a scraper just in case. Start with the clear side with no sidecar to get a feel for it. After doing that one tilt the sidecar for more clearance by pulling the top bolts off each mounting strut.


Take out the plugs. Take off the distributor cover. Take off the valve cover.


Turn the engine over until the points just open. One cylinder should be at the top of its travel and its two valves should allow you to rock the rocker arms. Loosen the lock nut with a wrench and slide the go feeler gage between the top of the valve and the rocker arm. You may have to turn the adjusting screw back and forth a bit until you can slide the proper section of the gage in and slide it with a small drag. Now loosen the screw just a tiny bit as when you tighten the lock nut it always changes, usually tighter. You may have to repeat this several times with each valve until you get the adjustment lock nut tight with a slight drag on the feeler gage. If you must err do so on the loose side as a valve will tick and you lose a tiny bit of power if it is loose. If you go too tight a valve can burn. Check the lock nuts one last time and inspect the valve cover gasket. If the gasket is damaged carefully clean the cover and apply sealer on the side that meets the cover. Apply the gasket to the cover making sure it is on straight and let it dry. I clean the head surface and apply a light layer of oil to the gasket mating surface. This is so you can reuse the gasket if you have to remove it on the road. Lightly tighten the valve cover hold down bolts (don't break them) and you are done one side.


Roll the engine over until the points start to open on the next cam and you are ready to adjust the other cylinder. Use a bit on Locktite on the strut bolts. If you can get an old VW manual it might help as it is much the same.


Jeff’s answer was much more thorough and shows that there is more than one way to skin a cat. I was going to take the best of both and co-mingle but I think some folks might benefit from the slightly different points of view. I learned to use the points to adjust valves by on multi cylinder engines as timing marks do not work on all cylinders. Either way will work fine on a Chang and if you check the hole for the timing mark you’ll see when the points open will be within a few degrees. All you have to be is on the compression stroke and on the back of the cam, there is quite a bit of latitude. I did this job on my Chang Hong water pumper so I have included pix of my other bike’s points distributor too. On the Chang Hong I have a Hall Effect electronic distributor and you can see the pencil mark on one side of the top. This shows me cylinder number 1. When the cutout is next to the magnet on 1 I adjust that side. A full rotation and the other cutout next to the magnet and I can adjust number 2. This works just like the points just opening on number 1 and 2.


I have also added a couple of pictures of the small valve cover bolts that my red bike has but the Chang Hong does not. On the Chang Hong improvements were made to a better gasket and the small bolts were replaced with pins. They also added clearance to adjust the valves without tilting the sidecar. As an aside you may need to use a shortie flat screwdriver like the one in the picture on the sidecar side. Because of the additional room, the improved reusable gaskets and having no need to tilt the sidecar the valve adjustment took me fifteen minutes on the Chang Hong. Figure another hour if you have to tilt the sidecar and scrape off old gaskets.