Taotao atm50 scooter sputtering  By  luminescence11 (Read 4,390 times)

May be a dirty carb or bad gas. Clean the carb the best you can as its a sealed carb from factory and try some known good petrol.

Check air filter for cleanliness and make sure your intake manifold isnt cracked. Check all vacuum lines also.

So after messing with it for the last couple of hours, I noticed the exhaust is kicking out some white smoke. Look at the carb, but it seemed pretty clean to me. Any idea what might be causing the smoke? Bad gas?

when you notice your scooter start to sputter look at the rpm gauge if it drops really fast its probably spark or something electrical also it would be a good idea to check the valve gaps

Does it backfire on deceleration? Have you tuned the carb at all? How much oil is your engine consuming? White or what looks like white smoke, accompanied by a smell of burning is usually oil burning. You may have one or a mix of a few problems causing this.

I would check the gas lines, and gas pump. Disconnect the gas line from the carb and vacuum hose from the intake manifold that connects to the gas tank, drain the gas that is inside the gas line into a cup or something, it shouldn't be much, if it does not stop draining you have a bad petcock, if it stops it should be fine. Suck on the vacuum line that leads to the gas tank gently to provide a vacuum and make sure some gas is coming out of the gas line (make sure to drain into something, and NO SMOKING while doing this!). If no gas comes out when providing suction to the pump that controls the gas then inspect the vacuum hose, if that is okay then replace the pump.

If everything is okay, you have successfully ruled out any problems with gas up to the carb, next is to inspect the carb, check it for dirt, any cracks in the air filter or connections may let sand or dirt in, it only takes one tiny grain of sand to clog your gas jets inside the carb. Once you have cleaned the carb, prime it with some fuel by providing suction to the fuel pump while the gas line is connected to the carb, then reattach the vacuum line to the intake manifold.

Still no good? Move on to electrical components, replace each part one by one, like test the spark plug by putting in a different plug, then put the one you already had back in if the new one has the same results, and then do the same for each other components, cdi, ignition coil, etc. I choose to pull and plug new parts/old parts because even with a multimeter electrical issues can check out alright until you are on the road and unable to stand next to it with a multimeter. Check to make sure all wires are still connected, after a while riding in rain or snow will rot the wires where they connect to the terminals on harnesses, I have chose to wire everything directly without harnesses so there are no exposed connection points. If you have rotted connections, cut then, get new terminal ends or try to gently pull the old ones apart with a knife and pliers, brush it off with a wire brush and reattach the new clean cut wire to the terminal.

Still no good? Disassemble your engine and take a look at the bore and the piston, look for scratches or noticeable wear, take a look at the rings around the piston, are they broken or bent or maybe just not on the piston all the way? Do the gaps look very big or very small?