The following three conditions mustbe satisfied for satisfactory engine start.
1.The cylinder filled with a proper
2.An appropriate compression in the cylinder.
3.Good sparks at the correct timeto ignite the mixture.
The engine cannot be started unless these three conditions are met. There are also other factors which make engine start difficult, e.g., a heavy load on the engine when it is about to start at low speed, and a high back pressure due t o a long exhaust pipe, just o say a few.
The most commoncauses of engine troublesare given below.
11- 1 STARTING DIFFICULTIES
1 1- 1 - 1 FUEL SYSTEM
1 ) No gasoline in the fuel tank; or the fuel cock is closed.
2 ) The carburetor is not choked enough, particularly when the engineis cold.
3)Water, dust or gum in the gasoline block flow of the fuel to the carburetor.
4)Inferior grade gasoline or poor quality gasoline is not gasified enough to produce the
5)The carburetor needle valve is held open by dirt or gum. This trouble can be detected as the fuel flows out of the carburetor when the engoneis idling. (Overflow)
This trouble may be remedied, depending on cases, by lightly tapping the float chamber with thegrip of a screwdriver or the like.
6)Ifthecarburetoroverflows, excessive fuelrunsintothecylinder when startingtheengine,makingthe
fewturns in orderto Iet the rich
st artagain.
7) When the engine is cold, pull the craburetor knob to let thegasoline flow into the carburetor.
11- 1-2 COMPRESSION SYSTEM
If starting difficultes andloss of power are not due to thefuel system or ignition system, the followings must be checked for possible lack of Compression.
1)Engine inside is completely dried upbecause of a long period of
2)Loose or broken spark plug. This causes a hissing noise made by mixture gas running out of cylinder in compression stroke during cranking.
3)Damagedheadgasket or loose cylinderhead. A similar hissing noiseisproducedduringcompression stroke.
4)IncorrectTappetClearance
If the correct compression is not obtained even after remedying the above, disassemble the engine and check further as follows:
a)Valve stuck open due to carbon or gum on thevalve stem.
b)If thepiston rings arestuckonthepiston,removethepistonandconnectingrodfromtheengine, and clean, remedy or replace the parts.
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