| Operation | Section reference |
| Remove the timing belt covers | N 4.2, Removal of the timing belt covers |
| Remove the valve covers | Removal of the valve covers |
Note: Engine timing should be checked after changing parts such as camshafts, valves or timing belt rollers or when overhauling badly worn engines.
Remove the spark plugs and install the tool (E) 88765.1297 in the spark plug bore to determine the piston's TDC, along with gauges (C) 88765.1581 and the timing check tool with timing degree wheel (G) 88713.0123).
Reset the opening valve clearance when the camshaft is in rest position by inserting a feeler gauge between the opening rocker arm and the opening shim.
Check that in this condition the camshaft can rotate. If it moves stiffly, use a thinner feeler gauge.
In this condition, with the piston of the horizontal cylinder is at TDC and the valves fully closed as confirmed by the reading on gauge (E), set gauges (C) to zero.
Adjust the timing belt tension as described in Refitting the timing belt tensioner pulleys.
Turn the degree wheel (G) counterclockwise until the dial gauge (C) on the exhaust side shows a lift of 1 mm. Check that the angular displacement reading on the degree wheel (G) is as specified (Timing system/valves).
Continue to rotate in the same direction until you obtain a 1 mm lift on the intake side. Check the angular value on the degree wheel.
Continue to rotate until, in correspondence with the closure of the valve for the compression stroke, you obtain a lift of the intake valve of 1 mm on the gauge (C). Check that the angular displacement reading matches the specified value (Timing system/valves).
Rotate clockwise again until obtaining 1 mm lift of the exhaust valve, on both valve opening and closure.
Check the angular displacement value against the specified value.
Repeat the procedure for the vertical cylinder.
Permissible tolerance for measured values is±3° with respect to specified values.
Remove the tools used to check engine timing.
| Operation | Section reference |
| Refit the valve covers | Refitting the valve covers |
| Refit the timing belt covers | Refitting the timing belt covers |