4. Maintenance
USE AND MAINTENANCE MANUAL
CHAPTER 4
MAINTENANCE
4-Strokes - Edition 00 / 2022
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A
3
2
1
A
A
2
1
4.5 VALVE CLEARANCE
Make sure that the valve clearance is controlled
and/or adjusted when the engine is cold (ambient
temperature).
While the valve clearance is checked and/or adjusted,
ensure that the piston remains at the top dead centre
(TDC).
Check
– Remove: Seat, left and right conveyors, air filter casing, fuel
tank;
– Remove spark plug and valve cover;
– Perform the engine timing operation (refer to section “4.4
Camshafts” on page 108);
– Measure the valve clearance “A” between the camshaft
lobes “1” and the valve lifters “2”, using a thickness gauge
“3”.
– If the clearance value of one or more valves is not within
the standard values, proceed with the adjustment.
Intake valve clearance (XXF 250 / XEF 250):
0.12 - 0.19mm (0.0047 – 0.0075 in)
Intake valve clearance (XXF 450 / XEF 450):
0.10 - 0.17mm (0.0039 – 0.0067 in)
Exhaust valve clearance (XXF 250 / XEF 250):
0.17 – 0.24mm (0.0067 – 0.0094 in)
Exhaust valve clearance (XXF 450 / XEF 450):
0.15 – 0.22mm (0.0059 – 0.0087 in)
Adjustment
– Check that the crankshaft and camshaft references are
correctly aligned with the references on the left crankcase
cover and cylinder head;
– Remove the camshafts (refer to section “4.4 Camshafts”
on page 108);
– Remove the valve lift “2” and the adjustment plate “3”,
relative to the valve to be adjusted, using a magnet “1”.
– Check the thickness of the adjustment plate by checking
the value “A” on the upper wall of the plate. If the value “A”
cannot be read, measure the thickness of the plate with a
micrometer.
– Choose the thickness of the new plate to be installed
according to the following formula:
A=(B-C) + D
A. New plate thickness;
B. Valve clearance detected;
C. Valve clearance specified;
D. Old plate thickness.