9.3 - | Crankcase assembly: crankshaft/connecting rods assembly

1 | Crankshaft

2 | Drilled grub screw

3 | Plug

4 | Grub screw

5 | Connecting rod assembly

6 | Bush

7 | Half bearing

8 | Special screw

9 | Shim

10 | Key

Parts catalogue

connecting rods

Important
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.
Removal of the crankshaft/connecting rods assembly

Operation | Section reference
Remove the engine from the frame | N 1, Removal of the engine
Remove the lubrication system | N 2.1, Removal of the oil pump
Remove the cylinder head assemblies and the timing parts | N 4.3, Cylinder head assemblies: camshafts
Remove the cylinder barrel/piston assemblies | N 5, Removal of the cylinder/piston assembly
Remove the alternator-side crankcase cover and the alternator assembly | N 8, Flywheel - alternator
Remove the engine starting system | P 3, Electric starting system
Remove the clutch-side crankcase cover | N 6.2, Removal of the clutch-side crankcase cover
Remove the clutch assembly | N 6.1, Removal of the APTC clutch
Separate the crankcase halves | N 9.2, Separation of the crankcase halves

After separating the crankcase halves, withdraw the crankshaft (1) complete with connecting rods (5).
Disassembly of the crankshaft/connecting rods assembly
To disassemble the connecting rod,/crankshaft assembly, undo the screws (8) and separate the connecting rod (5) from the crankshaft (1).
Important
Take care not to mix up components of different con-rods and maintain the original orientation.
Overhaul of the connecting rods
Make the following dimensional checks on the connecting rods:

- | assembly clearance with gudgeon pin at time of fitting (Sect. C 1.1, Cylinder/Piston).

In case of excessive wear, renew the connecting rod. The small end bushing must be in good condition and firmly driven into its seat. Check for parallelism error measured at 100 mm from the connecting rod longitudinal axis:
the value must be H-h less than 0.02 mm; otherwise, renew the connecting rod.
The diameter of the big-end must be within the specified tolerance limits (Sect. C 1.1, Cylinder/Piston).
It is preferable to use crankshafts and connecting rods of the same size class.
Renewal of the connecting rod bearings
It is good practice to renew the bearings (7) each time the engine is overhauled.
Replacement bearings are supplied ready for assembly and they must not be reworked with scrapers or emery cloth.
Renewal of the small end bushing
To renew the bushing (6) use the tool shown in figure to simultaneously drive out the old bushing and install the new one (A).
Position the new small-end bushing so that the split is at 90° relative to the upper hole in the small-end.
Drill lubrication holes into the new bushing in correspondence with the existing lubrication holes on the connecting rod small end.
Now ream out the bushing until the inside diameter (D) is 18.006 to 18.024 mm.
Crankshaft overhaul
The main bearing and big-end journals should not be scored or grooved;
the threads, keyways, and slots must be in good condition.
Check for fretting or burrs in the fillet between journal and shoulder.
Fillet radius: 1.5 mm.
With the aid of a micrometer, measure out-of-round and taper of the big-end journals, taking the measurements in various different directions (Sect. C 1.1, Cylinder/Piston).
Use a dial gauge to measure the alignment of the main journals by setting the crankshaft between two opposing centres (Sect. C 1.1, Cylinder/Piston).
Unscrew all the plugs (4), (3) and (2) from the crankshaft, heating the crankshaft, if necessary, to remove the threadlocker applied at the time of assembly.
Use a hot air gun capable of reaching 150 °C.
Clean all the oilways using suitable diameter metal brushes and then blow with compressed air to remove any residues that have accumulated and are restricting the oil flow.
Apply DUCATI liquid gasket on the threads of plugs (3), (4) and (2) and then refit the plugs.
Tighten all the plugs to the specified torque (Sect. C 3, Engine torque settings).
Big-end bearing shell-journal clearance
To check the assembly clearance between the bearing shells and crankshaft journals you will lay a strip (A) of GREEN “Plastigage PG-1” on the journal.
Fit the connecting rod with the original big-end bearing shells (7) (see procedure on next page) and tighten the bolts (8) to a torque of 49 Nm.
Remove the connecting rod and compare the width of the Plastigage strip to the scale (B).
If the width, which corresponds to the existing clearance, is not within the specified tolerance limits (big-end bearing shell-journal clearance indicated in Sect. C 1.1, Cylinder/Piston), it will be necessary to renew either the bearing shells or the crankshaft.
Reassembly of the connecting rods
Before starting, check that the crankshaft main bearing journals and big-end journals are free of burrs or evident signs of machining: if necessary, clean the surfaces with very fine emery cloth and oil.
Check that the grooves are in perfect condition with no signs of forcing.
Check that each connecting rod and cap are equipped with their locating pins (A).
Wash the pins and dry them with compressed air.
Clean and lubricate the journals and con-rod bearing shells with engine oil and fit the con-rods in their original mounting positions.
Fit the caps to the corresponding connecting rods. Make sure that the mark on the cap is the on the same side as the mark on the connecting rod.
Use the recommended grease to lubricate the threads and underside of the heads of the new screws (8) and the threaded hole in the connecting rod, packing in grease from both sides of the hole.
Warning
The grease utilised is an irritant in contact with the skin. Wear protective gloves.
Important
Lubrication of big-end cap screws is essential to obtain the correct coupling and to prevent breakage of the parts.
The connecting rod screws may be used and tightened once only, after which they must be discarded.
Temporarily fit the gudgeon pin (L) to align the connecting rods, and then tighten the screws.
Fit the spacer (H) of the tool 88713.2878 between the connecting rods and take up residual axial play with the fork feeler gauge (I) of the tool 88713.2878 which is available in the following thicknesses:
0.1 mm - 0.2 mm - 0.3 mm.
Tighten the screws (8) in three stages to the specified torque (Sect. C 3, Engine torque settings), using a torque wrench. Hold the wrench as shown in the photo.
Withdraw the feeler gauge and check that the connecting rod/crankshaft endfloat is: 0.15 to 0.35 mm.
Refitting the crankshaft/connecting rod assembly
Install the connecting rod/crankshaft assembly in the crankcase and follow the shimming procedure as described in Sect. N 9.2, Crankcase assembly: crankcase halves.
Important
Make sure that the connecting rods (5) are correctly positioned in the respective cylinder seats. Incorrect positioning of the connecting rods at this stage will inevitably lead to the need to re-open the crankcase.

Operation | Section reference
Refit the clutch assembly | N 6.1, Refitting the APTC clutch
Refit the clutch-side crankcase cover | N 6.2, Refitting the clutch-side crankcase cover
Refit the engine starter system | P 3, Electric starting system
Refit the alternator-side crankcase cover and alternator assembly | N 8, Flywheel - alternator
Refit the cylinder barrel/piston assemblies | N 5, Refitting the cylinder/piston assembly
Refit the cylinder head assemblies and the timing parts | N 4.3, Cylinder head assemblies: camshafts
Refit the lubrication system | N 2.1, Refitting the oil pump
Install the engine in the frame | N 1, Refitting the engine