19
VALVE SYSTEM
The overhead valves are operated by the camshaft via pushrods and rocker arms.
Tappet Clearance
§ to be checked and adjusted while the engine is cold
§ set the decompression valve twist grip in the “0” position
§ remove the rocker arm cover, attached with two studs and nuts
§ crank the engine until the compression resistance is clearly noticeable
§ use a feeler gauge to check the clearance between rocker arm and valve. Correct
clearance = 0.15mm (.006 in)
§ adjust if necessary by loosening the adjustment screw lock nut at the rocker arm
push-rod end – 1 –
§ turn the adjustment screw either way until the correct clearance is achieved
§ hold the screw in position while the lock nut is tightened
§ check the clearance once more
§ repeat the same procedure at the remaining valve
§ re-install the cover with a new gasket
The Decompression Valve
§ is checked and adjusted when the valve mechanism has been worked on or if the
proper setting has been altered for other reasons affecting the correct functioning
of the valve
§ remove the rocker arm cover
§ check and adjust the tappet clearance
§ turn the decompression handle to position “1”
§ undo the decompression valve adjusting screw locknut – 2 –
§ turn the adjustment screw counter-clockwise until the rocker arm clearance is
clearly noticeable
§ turn the adjustment screw clockwise until the rocker arm is just in touch with the
valve and then another half turn – 180
o
– in the same direction
§ hold the screw in position while the locknut is tightened
§ install the rocker arm cover and a new gasket
§ set the decompression valve twist grip in “0” position
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