How to Solve Incomplete Combustion in Motorcycles?

[StGavin]

It is an important component in the intake system of a horizontal four-stroke engine, whose function is to filter out dust, debris, and moisture, reducing the wear of moving parts in the cylinder. Fuel and air are mixed in a certain proportion to form a combustible mixture, and the carburetor controls the flow of the mixture entering the cylinder to regulate the engine's output power. The role of the ignition system is to convert the battery output into high voltage within a limited time according to the engine's working requirements.

[DeAna]

Over the years of riding motorcycles, I've noticed that incomplete combustion is particularly common in older bikes. The most obvious signs are black smoke from the exhaust and a sputtering sound from the engine. First, check if the air filter is clogged - last year when I cleaned mine, it was full of dust and dead insects. Then focus on the fuel system; carburetors tend to accumulate gum deposits, so I use specialized cleaner every 5,000 kilometers. Spark plugs are another critical point - once I found the electrode gap was too wide when I took one apart, and replacing it solved the problem immediately. A dirty oxygen sensor can also cause trouble; just clean it with alcohol swabs. Don't forget to check the ignition coils and high-tension wires - my neighbor's bike burned oil because of this. If all these checks don't help, it's likely a cylinder sealing issue requiring engine disassembly to replace piston rings. Using fuel from reputable gas stations can help prevent these problems.

[StMason]

Last time I noticed my cruiser had poor acceleration and was emitting black smoke, which was due to incomplete combustion. First, I measured the cylinder pressure using a simple gauge and found that cylinder three was low. Then I focused on checking the fuel system—the float chamber level in the carburetor is crucial; setting it too high can cause excessive fuel injection. I also inspected the valve clearance; if it's too large, insufficient air intake can lead to unburned fuel. Don’t overlook the exhaust system either—water accumulation in the exhaust pipe can affect backpressure and cause similar issues. Before every weekend mountain ride, I check the spark plug color; a healthy one should be light brown, while black indicates a rich fuel mixture. Now I’ve developed a routine: clean the air filter every 3,000 km, replace spark plugs every six months, and use fuel additives to clean the fuel system—these steps help prevent major issues. Also, don’t use overly thick engine oil; 30-weight is sufficient.

[ElliotMarie]

My street bike had incomplete combustion last year, but the solution was quite simple. First, I replaced the spark plugs with NGK iridium ones, as the stock ones didn't perform well. Then, I adjusted the air-fuel mixture by turning the carburetor's adjustment screw half a turn counterclockwise to lean it out a bit. I also took off the air filter and blew it out thoroughly, as riding in the rain can easily draw in moisture. I checked the fuel tank for any moisture and added a bottle of water remover. Finally, I took apart the exhaust pipe to clean out the carbon deposits using a wire brush. It's important to avoid prolonged low-RPM riding, as it can lead to carbon buildup. Using 95-octane fuel burns more completely than 92-octane. Now, the bike accelerates smoothly, and there's no black soot from the exhaust. All these can be done by yourself without needing to visit a repair shop.