How to Fix Black Smoke from Motorcycle?
2 Answers
Below is a detailed introduction to the repair methods for black smoke from motorcycles: 1. Replace with a slightly smaller idle jet. 2. Adjust the float height: Observe the fuel level in the float chamber; it should be at about 2/5 of the chamber for a normal level (Note: When opening the lower cover to check the fuel level, the carburetor must be held upright to prevent spilling gasoline, which could lead to inaccurate fuel level judgment). 3. There are three types of starting enrichment valves: (1) Manual plunger-type enrichment valve: Repairing a manual plunger-type enrichment valve is relatively simple. It can be fixed by cleaning the plunger, replacing the spring, or addressing the pull cord return issue. (2) Vacuum diaphragm plunger-type enrichment valve: For a vacuum diaphragm plunger-type enrichment valve, mainly check whether the vacuum tube or vacuum diaphragm is cracked or leaking. (3) Electric heating plunger-type enrichment valve: For an electric heating plunger-type enrichment valve, issues are usually due to damaged heating elements or faulty power supply lines. Damaged heating elements must be replaced. 4. Replace with standard new parts: If the gap between the needle jet and the main jet is too large, replace them with standard new parts.
When my motorcycle was emitting black smoke, I immediately thought it was due to incomplete combustion, possibly from too little air or too much fuel. First, check the air filter—if it's clogged with dust, simply clean or replace it, which isn't costly. A worn-out spark plug can also cause this; pull it out to see if the electrodes are eroded, and replace it if necessary. The fuel ratio needs to be adjusted correctly. If the carburetor setting is too rich, use a screwdriver to adjust the air screw to make it leaner. If you're using substandard gasoline, switch to standard fuel to avoid impurities. Also, rule out oil leaks or damaged seals. Riding on dirt roads often leads to dust buildup, so remember to clean the filter monthly—don't wait until it's broken to take action. After repairs, test ride for a while; if the smoke decreases, it means the fix worked.
