Carburetor: Dirt can get into the carburetor. Clean it every 5.000 miles/ 8.000 kms. Take off the float chamber. Take out the float. Check the top of the float. It must be put in again the same way. Wash both in petrol. Move the needle valve with your finger.
On the side of the carburetor there are two screws. One controls the slow running of the engine. The other controls the richness of the mixture. They can be screwed in and out. This needs some practice to have the engine run slowly and with the right mixture.
Sometimes the starter turns the engine but the engine will not start. There may be too much mixture in the cylinders. To get it out, push the accelerator pedal down to the floor. Start the engine again. This will often push the mixture out of the cylinders. The car will now start in the usual way.
Air cleaner: This is on the top of the carburetor. Clean this also. Some can be cleaned with petrol.