4. Maintenance
USE AND MAINTENANCE MANUAL CHAPTER 4
MAINTENANCEXEF 250 - Rev01 / 2020
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FWD
4.6 CYLINDER HEAD
Removal
– Remove: Seat, left and right conveyors, air filter casing, fuel
tank;
– Remove the spark plug and valve cover;
– Remove the camshafts (refer to chapter “4.4 Camshafts”
on page 65);
– Remove the nuts and bolts securing the head to the
cylinder;
Loosen the bolts ½ turn at a time, following the
sequence shown in the figure.
– Remove the bolts after having completely loosened each
one.
M9 x 135mm (5.31 in): “4”, “5”, “6”
M9 x 145mm (5.71 in): “3”
– Remove head “1” from the cylinder, gasket “2”, centering
pins “3” and timing chain guide “4”;
Check
– Remove carbon deposits using a rounded scraper;
Take care to avoid damaging the spark plug threads.
Do not use a sharp instrument. Avoid scratching the
aluminum.
– Check the head for damage and/or cracks, if any, replace
the head;
– Check the water circuit, if there is encrustation and/or rust
replace the head;
– Measure the deformation of the head, if it does not conform
to specifications, level the head.
Maximum permissible deformation:
0.05 MM (0.0020 in)
If it is necessary to replace the head, the valves must
also be replaced.
Installation
– Wash the threads and contact surfaces of bolts, washers,
head/cylinder contact surface and crankcase threads;
– Install the gasket, centering pins, timing chain guide and
head;
– Apply molybdenum disulphide grease to the threads and
contact surfaces of the bolts and washers;
– Install washers “1”, bolts “2” and nuts “3”.
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