Unscrew the bolts securing the coolant pipe union (arrowed)

5Unscrew the bolts securing the coolant pipe union to the rear of the cylinder head (see illustration).Discard the O-ring as a new one must be used.

6 The cylinder head is secured by eight 9 mm bolts and two 6 mm bolts (see illustration).First slacken and remove the two 6 mm bolts located in the cam chain tunnel. Note their positions as they are of different lengths. Now slacken the remaining bolts evenly and alittle at a time in a criss-cross sequence, working from the outside towards the centre, until they are all slack and can be removed with their washers (see illustration).

A 9 mm head bolts (A) and 6 mm head bolts (B)

10.6b Removethe head bolts with their washers

2*16 Engine, clutch and transmission

Secure camchain with length of wire (arrowed)

7Pull the cylinder head up off the block (see illustration).If it is stuck, tap around the joint faces of the cylinder head with a soft-faced mallet to free it. Do not attempt to free the head by inserting a screwdriver between the head and cylinder block - you'll damage the sealing surfaces. While removing the head, ensure that the camchain does not fall down into the crankcase.

8 Remove the old cylinder head gasket and discard it as a new one must be used. If they are loose, remove the two dowels from the front outer bolt holes in the cylinder block. If they appear to be missing they are probably stuck in the underside of the cylinder head.

9 Check the cylinder head gasket and the mating surfaces on the cylinder head and block for signs of leakage, which could indicate warpage. Refer to Section 12 and check the flatness of the cylinder head.

10Clean all traces of old gasket material

Clean jointing faces of cylinder head and block thoroughly

from the cylinder head and block (see illustration).If a scraper is used, take care not to scratch or gouge the soft aluminium. Be careful not to let any of the gasket material fall into the crankcase. the cylinder bores or the oil and coolant passages.

Installation

11Lubricate the cylinder bores with engine oil. If removed, install the dowels into the front outer bolt holes in the cylinder block (see illustration).

12Ensure both cylinder head and block mating surfaces are clean, then lay the new head gasket in place on the cylinder block. Make sure all the holes in the gasket are correctly aligned and that it locates correctly onto the dowels. Check that the 'YUP' lettering stamped out of the gasket is positioned along the rear edge and is the correct way up (see illustration).Never re-use the old gasket.

10.11 Install dowels in the cylinder block.,.

13Carefully lower the cylinder head onto the block while feeding the camchain up through the head. Make sure the head locates correctly onto the dowels and secure the camchain with a length of wire to prevent it dropping into the crankcase.

14 Apply clean engine oil to the threads and seating surfaces of the cylinder head bolts and install all the bolts and washers and tighten them finger-tight. First tighten the eight 9 mm bolts evenly and a little at a time in a criss-cross pattern, starting from the centre and working outwards, to the torque setting specified at the beginning of this Chapter (see illustration).Then tighten the two 6 mm bolts located in the camchain tunnel to the specified torque.

15 Fit a new O-ring onto the coolant pipe union and secure it to the rear of the head with the bolts (see illustration).

16Lubricate each valve shim with a 50/50 mixture of molybdenum disulphide grease and engine oil and fit it into Its recess on the top of the valve, with the size marking on each shim facing up (see illustration).Check that the shim is correctly seated, then lubricate the follower with molybdenum disulphide oil and install it onto the valve (see illustration). Note:/(is most important that the shims and followers are returned to their original valves otherwise the valve clearances will be inaccurate.

17Install the camshafts (see Section 9).

18 Install the exhaust system and the carburettors (see Chapter 4).

19 Fill the cooling system (see Chapter 1).

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Date: 2016-01-14; view: 1453