Valve Clearance - Mash Side 400 Mode D'emploi

4.

Valve clearance

Noise will stem from too big valve clearance. However if
there is too small gap or even no gap at all, closing of the valve
will be hindered, which will cause many problems such as engine
stall, power loss, etc. Therefore, the valve clearance must be
checked periodically.
The valve clearance should be inspected and adjusted on a
cold engine by the following procedures:
Remove the caps of the central hole and the ignition timing
observation hole on the left crankcase cover.
Remove the caps of the two air valves on the cylinder head.
Turn the nut of the flywheel clockwise until the engraved "T"
mark on the flywheel aligns with the engraved line on the top of the
crankcase cover, and both intake and exhaust rock arms do not
move but stop at their loosest position, which shows that the piston
is in its top dead center position of the compressing stroke. If the "T"
mark is near its right position but rock arms will move apparently
when flywheel rotate a small angle, the flywheel is not in the
compressing stroke but exhaust/intake stroke. In this case,
continuously turn the flywheel clockwise for 360 degrees to the top
dead center position of the compressing stroke, where the valve
clearance can be adjusted. Afterwards, check the valve clearance
by inserting a clearance gage into the gap between adjusting screw
and the end of the valve.
The specified valve clearance is : 0.07-0.10mm for intake
valve and 0.08-0.12mm for exhaust valve respectively.
If clearance adjustment is needed, loosen the locking nut on
the rock arm, turn the adjusting nut till a slight resistance is felt on
the inserted right clearance gage.
At the end of the adjustment, tighten the "Locking out "to
prevent loosening and another check to make sure that the valve
clearance is OK before all those dismounted caps are refitted on.
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Upper eyehole cover
Eyehole cover