Due to the gas valve damage, or not sealed, or open close is not correct, resulting in reduced effective power of the engine, resulting in weak engines, fuel increased. Serious engine spontaneous combustion. Especially when you replace the air filter, if the air filter cartridge is found in the box with the oil pollution, it is best to do an engine repair, check the working status of the gas valve. Whether it is not sealed, is opening timing. The linkage rod with the chicken mandrel, under the traction of the chain or pulley, acts exactly on the push rod end of the gas valve and opens the intake port or the exhaust port. Again in the spring reaction force, close the cylinder inlet, or exhaust port, back and forth to work. Meticulous inspection work, is to use a special tool, first compressed gas valve springs, remove the gas valve fixed steel lock ring. According to the order of remembering the corresponding cylinder sequence. Then take a gas valve, at the end of the canopy, use a chalk mark, insert the gas valve seat, and gently turn the throttle. Take it out and see if the chalk marks all disappear, indicating that the gas valve is sealed. If the mark sometimes no, then the gas valve damage, has lost the role of seal. The next process is to polish the gas valve. Because it is working in a hot environment, the shape of the valve stem may be deformed. With a precision instrument can measure out, gas valve steel pole activity space, whether serious wear and tear. Or because the deformation of the steel is simply not up and down activities. When adjusting the gas valve, the minimum distance between the center of rotation on the transmission rod and the top of the steel rod of the gas valve is generally 0.25-0.33mm, and the distance between the steel blades is measured. Also based on the engine ignition sequence 1-2-4-3, or 1-3-4-2 to accurately regulate the gas valve opening or closing sequence and time. As the engine is working under pressure, the last in the back cover, the lid seal is not sealed, a direct impact on the work of the engine power is good or bad. It must be in accordance with the standards, how much torque, a good fixed high temperature, high pressure gaskets. In order to get a powered engine.