Ok, first of all, this goes without saying, you have to clean your carburetor, here are the instructions I used for Dellorto 14 12 carburetor: take the carburetor off your bike, (there’s usually just 1 screw on the carburetor which holds it to intake valve once you loosen it, you can wiggle carburetor away from the engine) on the bottom of your carburetor, remove the float bowl (it’s black plastic attached using 2 metal screws to the bottom of your carburetor), inside it you will see a golden screw which is the “main jet” remove it, there’s a tiny hole in it blow air trough it so that you can see trough that hole or use fine thin wire to clear it. Clean the passage way which you removed the main jet from, remove the float (float is ring shaped plastic) to remove it you have to first remove little silver pin that holds it, there’s also a small golden stick with rubber triangle end attached to the float, remove that as well (make sure you don’t spray any carburetor cleaner on that rubber triangle). Also don’t forget to clean the Idle hole: idle hole location The part where gas line goes into carburetor, unscrew that piece, there’s a round filter underneath, which keeps nasty stuff from entering your carburetor, remove that filter and clean underneath it as well, clear all the passage ways inside your carburetor. Here is some more info on cleaning carburetor: carb cleaning info
When you attach the carburetor back, make sure its moved all the way in on an intake valve and before you tighten that screw, also make sure the carburetor is vertically straight, not at an angle, I have an older Dellorto carburetor with longer external choke lever, so I used to twist my carburetor at an angle because the choke lever wouldn’t go down all the way – BIG MISTAKE don’t do it, it’s better to bent or cut the choke lever a bit at the end so that it functions, but fit that carburetor straight vertically.
Missing side cover tip
If your moped is missing side covers and you can’t find or afford replacement ones, you can make some yourself using cut water-bottles and some duct tape (I used gorilla tape as it’s very strong). Covering sides of your moped is very important as it will protect carburetor & other parts from weather elements.
Tomos recommends using Octane Gas of 90 or higher, so I’m using highest octane possible.
For fuel line it might be a good idea to use clear fuel line, this way you can see if gas is actually going into your carburetor, I purchased this clear tube from home depot: “Watts 5/16 in. OD x 3/16 in. IDClear PVC Tubing.”
It might also be a good idea to use a fuel line filter a specially if your tank had rust in it. The fuel filter I used was “Duralast” FF2314DL purchased it from AutoZone for 6 bux. In order to attach it to the clear plastic fuel line (purchased earlier) had to use lighter to heat up the tip of the line to make it softer temporarily so it could be attached to the filter easier.
After swiping finger inside tank – it was rusty, had to clean it out, so I drained the fuel from the tank, removed petcock (petcock is the gas switch that can be removed from the tank using adjustable wrench) petcock was filled with dirt and rust, so it had to be cleaned, then plugged petcock hole & filled gas tank with 1 gallon of Apple Cider Vinegar (contains 5% acid) for about 20 hours (the longer the better) then used glass cleaning brush (attached longer handle to it using gorilla tape) and scrubbed the inside of a tank, then drained the vinegar, cleaned with gallon of water then filled with mix (gallon of water, half cup baking soda few squirts of liquid soap) to neutralize the acid, let this mix sit there for 20 minutes then washed it out with 3 gallons of water, drained all of the water out completely (had to flip moped on the right side a bit to get all of the water out) then filled it with some gas, used the brush to scrub on the walls of tank, rinsed/drained the gas out and then immediately filled with fresh gas to the top to prevent tank from rusting.
You can also test your engine for compression, if you don’t have compression kit, you can try this: take out the spark plug wet your thumb and press it firmly against the spark plug hole covering it completely, have your friend kick-start the moped while your covering that hole firmly, the air build-up inside should kick your finger away from the hole. Using this test, my moped was good enough to run, but of course it’s better to have an actual compression kit to see what your PSI level is (over 100 is good).
Check for spark plug if it has spark: remove the spark plug, wipe it off, attach it to the spark plug cable while the spark plug is outside of the cylinder, you can use some duct tape (or even better gorilla tape) to attach it to the outside of engine’s metal grill (metal bottom side of the spark plug has to touch the grill firmly) make sure there’s no gas on the grill or anywhere near, also it has to be dark or night time then use kick-start and look at the spark plug’s tip to see if there’s a spark.
You can remove the fly-wheel to get to ignition points, the fly-wheel is located on the left side of the motor (the side where the chain is at) you will need “L” shape key wrench to remove 3 screws to take off the flywheel cover, then use some sandpaper to clean those points. You may want to be careful with which solvents you choose and the type of sandpaper you use