Check-Up & Adjustment Of Air Valve Gap - Serpento SPIRIT 250 Manual De Usuario

Check-up & Adjustment of Air Valve Gap
Noise will stem from too big gap of the air valve .However if there is too small gap or even no gap at all , closing of the valve will be hindered
,which will cause burn of the valve and output drop .Therefore ,the air valve gap must be checked periodically .
The gap of the air valve should be inspected and adjusted with a cold engine by the following procedures:
1) Remove the caps of the central hole and the top holed (the ignition timing observation hole) in the left crankcase cover.
2) Remove the caps of the two air valves on the cylinder head.
3) Insert the "T" key into the central hole of the crankcase cover, jam it against the nut of the flying wheel and then turn the flying wheel clockwise
until the engraved "T" mark on the flying wheel aligns with the engraved line on the top of the crankcase cover .Swing the rocking arm slightly
.A loose rocking arm (which indicates the existence of clearance )shows that the piston is in the lower stop position of the compressing stroke
.In this case ,continuously turn the "T" key clockwise for 360 degrees until the alignment of those engraved marks ,where the valve can be
adjusted. Afterwards, check the valve gap by inserting a feeler in the valve adjusting screw and the end of the valve.
The specified air valve gap: 0.05mm for the intake and exhaust valves respectively.
4) If the adjustment needed ,loosen the locking nut of the valve ,turn the adjusting nut till
a slight resistance is felt on inserting the feeler .
Valve cap
At the end of the adjustment ,tighten the "Locking out "to prevent
loosening and another check to make sure that the valve gap is OK before all those
dismounted caps are refitted on .
central hole cap .
Central hole cap
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