Common faults of motorcycle

Common faults of motorcycle
Generally, the starting difficulties mainly include failure to start at all, failure to start in the morning, failure to start after stopping, failure to start when restarting, etc. The reason may lie in the ignition system, fuel system and compression process. In any case, there are three elements for engine starting, i.e. "sufficient compression pressure, strong spark timing ignition and proper fuel mixture". If these three elements are provided, the engine can be started normally.
A. If the compression process is abnormal, the compression pressure will drop. In many cases, the reduction of compression pressure will cause flameout and start-up difficulties. In this case, by measuring the compression pressure and checking the valve clearance, we can grasp the general reason. The main reasons for the decrease of the compression pressure are the loss of the cylinder stung ratio, the live stock Wear of piston ring and neon cylinder, poor sealing of crankcase mating surface, poor valve fitting, abnormal valve phase, poor fitting of sleeve valve, etc. The main reasons for the high shrinkage pressure are carbon deposition in the combustion chamber and on the top of the piston.
B. If the fuel system is abnormal and the proper mixture cannot be obtained, it will be difficult to start the engine. The main reasons for no fuel or insufficient fuel supply are: no fuel in carburetor float chamber, stuck needle valve, blocked fuel pipe and filter, blocked fuel tank cover, etc. The main reasons for the difficulty of cold starting in the morning are that the volatility of gasoline is poor under low temperature conditions, and because the viscosity of engine oil increases under low temperature conditions, the internal resistance of the engine increases and the rotation speed decreases, so the air flow rate also decreases, resulting in insufficient atomization of gasoline. Stop the engine after driving. The reason why the engine cannot be started again is that the fuel temperature in the carburetor rises due to the high engine temperature, which causes the fuel in the float chamber to boil and causes the mixture to be too rich to start.
C. The reason for the ignition system is that it cannot obtain a strong spark and is extinguished. The main causes of this phenomenon are insufficient current, incorrect ignition timing and spark plug failure. The reasons for insufficient current include electrical wiring failure, main switch failure, engine shutdown switch failure, ignition coil failure, magneto failure, spark plug cap failure, battery failure, etc. The main causes of spark plug failure are calorific value discomfort, electrode wear, ceramic part fracture, gasket depression fracture, carbon deposition, etc.
(2) Insufficient power
Complaints about insufficient power are almost manifested in "insufficient power", "poor speed", "poor acceleration" and so on. The causes include engine failure (fuel system, air intake system, exhaust system, cooling system, compression process, ignition system, lubrication system), transmission system failure (clutch, wheel, transmission chain, transmission, gear shift), brake system failure (brake caliper, disc brake pad), etc.
A. Most of the fuel system problems are caused by too lean fuel mixture and insufficient intake air. Check the carburetor and oil circuit for faults. B. In terms of the air intake system, the increase of air intake resistance and insufficient air intake lead to a decrease in the success rate. Check the air filter, reed valve, etc.
C. The exhaust resistance increases and the engine speed does not go up, so enough fuel mixture cannot be sucked into the combustion chamber, resulting in insufficient power.
D. Overheating and supercooling of the engine may cause power reduction. The causes of overheating include overheating caused by harsh operating conditions, overheating caused by poor cooling system, overheating caused by improper adjustment or maintenance.
E. Insufficient compression pressure will also cause insufficient power
F. Clutch slippage, tire underinflation, transmission chain elongation and brake slippage may cause insufficient power. (3) Abnormal sound and noise of engine
Various noises and abnormal sounds may be generated during the operation of the engine, but different judgment results will be obtained according to different personal experiences when judging whether the engine is abnormal or not. Common abnormal sounds are as follows:
A. Piston knocking sound (clang): the knocking sound is loud when the engine temperature is low, and becomes smaller or stops as the temperature rises. The reason may be the lateral knocking of the piston. B. Jacking rod sound (creaky creaky): the sound is low when the temperature is low, and the sound of jacking rod becomes loud after preheating; Suddenly make a loud push sound during driving. The reason may be poor contact between the valve and the valve seat.
C. Chain sound (rattle / chatter): this sound is made when the engine is started and disappears after a while. The reason may be poor chain tensioner.
D. Piston ring noise (Guli Guli): it may be caused by wear of the piston ring. Check whether the piston ring is damaged and whether the opening clearance and side clearance are normal.
E. Connecting rod big end noise (clattering): the gap between connecting rods is large, so the vibration is also large, and the speed increase is more serious. The reason may be the wear of connecting rod big end bearing and crank pin.
(4) Three common ignition methods for motorcycles