market dynamics
Can you tell a motorcycle is out of order by looking at its exhaust color?
Release date:2020.06.29

1.The exhaust gives off black smoke

Black seems to be a depressing color. If it weren't for the early two-stroke bikes that burned mixed oil (happiness XF250, etc.), there was only one reason for their "butt" to smoke: too much mixture. That is to say, the gasoline content in the cylinder mixture exceeds the normal level. The gasoline is not completely burned in the combustion chamber, and carbon particles are separated out along with the exhaust gas.

Faults can arise from the following aspects:

The air filter is blocked and less air enters. Carburetor fault, such as compensation or idle air channel blockage, insufficient air intake; The oil level of float chamber is too high, and some gasoline is driven directly into the cylinder without atomization, resulting in incomplete combustion. The main gauge hole is seriously worn, which makes the main nozzle oil injection volume increase and causes incomplete combustion. The starting heating automatic valve is in the open position, the thickening valve cannot be closed automatically, resulting in too much mixture. An electric spray truck without a carburetor may have a sensor that is not working properly and cannot provide the correct information to the valve computer. In addition, muffler carbon blockage, exhaust not free, exhaust gas trapped in the cylinder, so that the fresh air combustion is not sufficient, will take black smoke.

The above faults, if not eliminated in time, will lead to the accumulation of carbon on the valve, affect the tightness of the combustion chamber, resulting in the engine power decline, slow acceleration, boring. Stop and repair immediately, troubleshoot in time.

First check the air filter for blockage. If the paper filter element of the air filter, generally to replace the filter element. If the foam plastic filter element is used, the filter element should be cleaned in kerosene or non-combustible detergent. After drying, the surface should be coated with a small amount of lubricating oil (be careful not to paint too much, otherwise the air intake will be reduced). After cleaning the filter wall, the filter element should be installed again.

Check the carburetor again after making sure the air filter is fine. For plunger type throttle carburetor, use compressed air to blow out all holes and passages and check that the main oil needle is in a proper position. The card shall generally be located in the third slot. If the main needle is overworn, the float needle valve shall be replaced with the needle seat. If the main gauge hole is seriously worn (usually due to the enlargement of the inner diameter caused by the removal of foreign bodies with iron wire during maintenance), a new main gauge hole should be replaced. To check whether the float height is appropriate, turn the carburetor upside down, remove the float chamber so that the float tongue depressions the float needle valve, and measure the distance from the float chamber junction surface to the top of the float (i.e., the float height), both sides should be consistent. For example, CG125 is 18.5mm, JH70 is 20mm, AND CJ750 is 22mm. If it does not fit, detach the float and adjust the float tongue with needle-nosed pliers.

Cars using vacuum diaphragm carburetors (e.g., Honda CH125, Homag 125, Suzuki AN125, AN150, etc.) should also be inspected for starting heating automatic valves. The specific method is: will start the heating valve of the yellow wire battery positive, green wire battery negative, about 5 minutes later, and then connect the polyethylene pipe to the fuel increment circuit, blow with the mouth to see, at this time the fuel increment circuit is fully closed, stuffy; If it can ventilate easily, it indicates that the automatic valve cannot close the fuel increment loop and should be replaced with the starting heating automatic valve.

The fuel consumption of electric jet motorcycle is very low, generally will not appear mixture too thick phenomenon. In case of such failure, the general maintenance personnel can not repair, only those trained professionals and manufacturers can repair, must not be dismantled at will, so as not to damage the computer, causing greater losses.

2. Blue smoke from the exhaust

Blue is a melancholy color. If your car's exhaust is blue, your mood will not be happy, indicating that the engine is burning oil. This is mostly due to the following reasons:

The gap between the cylinder and piston or valve and valve guide is too large, too much oil into the cylinder, most of it occurs in the long service life of the motorcycle, so regularly check the gap between the two, prevent excessive wear is very important. In addition, the oil in the sump of the four-stroke car added too much oil, splash lubrication, a large amount of oil into the cylinder, is also one of the reasons for the blue smoke exhaust.

When checking the gap between cylinder and piston, the wear of piston and piston ring should be checked. When repairing, the diameter of piston skirt should be measured. If the wear limit is reached, the piston should be replaced. Also check and measure the piston ring clearance, elasticity and light leakage, if damaged, broken or to the limit, the piston ring should be replaced. For installation, the chrome plated ring shall be installed in the first ring slot and the carbon steel ring in the second slot. Inscribed on the torus (e.g., T, N, R, UP), the inner chamfered groove is upward, the outer chamfered groove is downward, the ring mouth is away from the center of the pin hole and evenly staggered along the circumference. There is no direction requirement for the upper and lower blade of the combined oil ring, but the blade opening should be about 20mm away from the opening of the lining spring, and pay attention to the piston ring opening deviating from the direction of lateral pressure on the piston.

When checking the gap between the valve and the valve guide, the wear condition of the valve stem outside diameter and the valve guide inside diameter should be emphasized. When repairing, use outside micrometer to measure the diameter of the valve rod. If it reaches the limit, replace the valve and grind with the valve seat. Before measuring the valve catheter, insert the reamer into the catheter to remove carbon deposits (see Figure 4). The reamer should be rotated to the right at the same time when the reamer is entered or taken out. If the reamer is inserted or taken out directly after the reamer is rotated to the left or not rotated, the inner surface of the catheter will be damaged. The inner diameter of the valve guide tube shall be measured with an inner diameter dial meter (see Figure 5). If it is larger than the limit size, the valve guide tube shall be replaced.

Valve guides are divided into two types, flanged and unflanged. The replacement steps of valve guides with flanges are as follows:

1. Evenly heat the valve to 100℃ ~ 150℃ (put in the oven). Do not use gas flameter for local heating to prevent deformation of the cylinder head;

2. Knock out the valve guide with a special tool and be careful not to damage the cylinder head joint surface;

3. Apply lubricating oil on the new O-ring seal ring and install it on the valve conduit;

4. Embed the valve tube from the side of the camshaft before the cylinder head cools;

5. Reamer should be used for hinge light of valve guide pipe. Reamer should not be askew during reamer cutting.

The method for replacing the valve guide without flanges is the same as the above method, except that the height of the valve guide exposed to the cylinder head should be measured with calipers between the removal of the valve guide and recorded so that the valve guide can be installed back at the original height. In addition, loose valve ducts or damaged gaskets on the cylinder head can cause oil to burn. The valve guide fits into the cylinder head. If it becomes loose, the lubricating oil will leak into the exhaust duct (horizontal engine) or into the combustion chamber (vertical engine) for combustion. Valve guide should be replaced at this point, pay attention to the replacement after heating the cylinder head gently drive. If the cylinder gasket breaks next to the oil channel hole, causing the oil to be sucked into the combustion chamber, the fault can be eliminated by replacing the new cylinder liner.

3.The exhaust gives off white smoke

White symbolizes purity, which almost all people can confirm and accept. But when the exhaust is thick and white like milk, you have to think twice.

The thick white in the tail gas is natural because the content of water in the exhaust is more. Either you've been tricked into putting too much moisture in the gasoline, or you've been tricked into putting too much moisture in the gasoline. Either the problem is the motorbike -- the watercourse seals are broken, the liner is broken, the cooling water is getting into the tank (in the case of a water-cooled engine). When the gasoline mixed with water, in addition to the exhaust white smoke, will also produce exhaust pipe shooting, carburetor reverse injection and other faults, is very harmful to the engine, should be promptly removed in the fuel tank and oil line water gasoline. If the watercourse gasket of water-cooled engine is damaged, it should be replaced in time. If the cylinder liner is damaged, it should be repaired or replaced by professionals.