Cylinder Pressure; Timing Chain Tension - Shineray XY400-2 Maintenance Manual

XY400–2 Maintenance Manual
While aligning
The boss is in the center of the hole

Cylinder pressure

When the engine fails to start or is difficult to start, or
when questioning the cylinder pressure is abnormal
after other possible faults have been excluded, check
the cylinder pressure.
Cylinder pressure: ≥0.8MPa/300r/min.
While testing, remove the spark plug and mount a
pressure gauge at the position where the spark plug is
mounted; fully open the throttle bar and electronically
start the engine, and then check all connecting points of
the pressure gauge for gas leak. Zero the pressure
gauge and restart the engine until the pressure gauge
reading stops rising. The maximum reading of the
pressure gauge can usually be reached after 1 or 2
startups. Such maximum reading shall be the cylinder
pressure. Upon completion of testing, mount the spark
plug to its original position.
The main reasons for insufficient cylinder pressure
include:
Incorrect valve clearance adjusted

Valve leakage

Cylinder head sealing gasket ablated

Piston ring or cylinder worn

Piston ring worn

The main reasons for excessive pressure include:
Presence of accumulated carbon inside the
combustion chamber or on the piston top
Turn the key clockwise
Test cylinder

Timing chain tension

Start the engine to run at idle speed.
Carefully listen to the sound given off by the running
engine: if the timing chain gives off ringing sound
"Dah-Dah", it indicates insufficient tension of the chain
tensioner, replace it with a new one.
To replace the chain tensioner:
Unscrew the 2-M6×16 socket cap screw to remove the
sealing washer and detach the old chain tensioner.
Take care not let the sealing washer and so on fall into
26
Inspection and adjustment
Press engine's start button