Car black smoke, blasting cause of the malfunction and repair

Symptom: The car digiprog 3 is moving when the engine exhaust black smoke, exhaust pipe abnormal sound (shooting).
Cause:
1, the mixture is too thick, the cylinder mixture excess air ratio is too small, incomplete combustion, part of the fuel at high temperatures decompose into free carbon from the exhaust pipe, and the formation of black smoke.
2, the ignition timing is inaccurate, but also make the mixture incomplete combustion; or minority-cylinder engine does not work, there will be a small amount of smoke discharge.
Troubleshooting:
1, if the engine galletto 2 exhaust pipe a lot of smoke, accompanied by a discharge guns, you can conclude that due to the mixture too thick. Should promptly check the choke is fully open, if necessary, for high-speed access; flameout mouth after watching from the carburetor main nozzle, if the oil injection or drip out, then the float chamber oil level is too high, should be adjusted to the specified range, tighten or replace the main jet; clogged air filter should be cleaned or replaced.
2, If the engine launch creader vi exhaust pipe a small amount of smoke, and is accompanied by the rhythm of the "chug" sound, you can conclude that a minority cylinder does not work or ignition timing misalignment due. Available by law to identify the cylinder misfire cylinder does not work, or check the ignition timing correction