Bold reference numbers in this section identify parts not shown in the figures alongside the text, but which can be found in the exploded view diagram.

Remove the inspection cover (A) and install service tool no. 88713.0123.

Turn crankshaft with tool no. 88713.0123, and set it so that the horizontal piston is at the TDC in the combustion stage, i.e. the valves of the horizontal head are all at rest position: check the valve clearance on the horizontal cylinder head. Set the degree wheel of service tool no. 88713.0123: to zero the horizontal cylinder is at top dead centre of the expansion stroke, and therefore we can proceed to check the valve clearances on this cylinder.

To measure valve clearances in the vertical cylinder, rotate the crankshaft counterclockwise through 270° from this position. This will bring the vertical cylinder to top dead centre of the expansion stroke, and therefore we can proceed to check the valve clearances on this cylinder.

While inserting the blade of the feeler gauge to check the clearance, apply gentle leverage to overcome the force of the closing rocker spring and thus eliminate any play in the rocker mechanism: then check that the shim can rotate freely.

The clearance values must be within the specified limits (Sect. 3 - 1.1, Timing system/valves).

If not, remove the opening shim (3), as described in chapter “Removal of the cylinder head assembly”, Sect. 9 - 4.4, and replace it with one of suitable height to obtain the prescribed assembly clearance.

To check the valve closing clearance, insert a feeler gauge between the closing rocker (D) and the shim (1): the closing clearance (Sc) corresponds to the thickness of the feeler gauge and should allow the free rotation of the shim without any significant play.

The value must be within the prescribed ones (Sect. 3 - 1.1, Timing system/valves).

If not, remove the closing shim (1), as described in chapter “Removal of the rocker arms, shims and valves”, Sect. 9 - 4.4, and replace it with one of suitable height to obtain the prescribed assembly clearance.

Refit the opening and closing shims as described in the paragraph “Refitting of the rocker arms, shims and valves“, Sect. 9 - 4.4.

Fit the gauge (C) 88765.1581 in correspondence with the fixing hole of the previously removed head valve cover, as shown in the figure.

Reset the valve opening clearance when the camshaft is in its rest position by inserting the blade of a feeler gauge between the upper rocker arm and the opening shim.

Check on the dial gauge that the measured value corresponds to the prescribed one (Sect.  3 - 1.1, Timing system/valves).

Perform the same procedure for the exhaust valve, fixing the support to the opposite side of the cylinder head.

Refit the components by carrying out the same Operations indicated in chapter “Checking and adjusting valve clearances”, previously described.

Remove the tools 88765.1581.

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 recess 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.

In this condition, with the piston of the horizontal cylinder at TDC and the valves fully closed as confirmed by the reading on dial gauge (E), set gauges (C) to zero.

Set the tension value of the belts as described at Sect. 9 - 4.2, Refitting the timing belt tensioner pulleys.

Turn the degree wheel (G) counter clockwise until the gauge dial (C), on the exhaust side, shows a lift of 1 mm. Check that the value of the angular displacement read on the degree wheel (G) is as specified in (Sect. 3 - 1.1, Timing system/valves).

Continue to rotate in the same direction until you obtain a lift of 1 mm 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 the angular value with the prescribed one (Sect. 3 - 1.1, Timing system/valves).

Rotate clockwise again until obtaining 1 mm lift of the exhaust valve, on both valve opening and closure.

Permissible tolerance for measured values is ±3° with respect to specified values.