A Upper crankcase bolts (A), lower crankcase bolts (B) - 21.4b Upper crankcase bolts (A), lower crankcase bolts (B) -

J and К models L, N and R models

Numbers indicate the tightening sequence Numbers indicate the tightening sequence

Engine, clutch and transmission 2*39

21.9 Carefully separate the halves

21.10 Remove the three dowels (A) if loose, and the two oil nozzles (B)

remove them (see illustration 21.4a or b).

Note: /Is each bolt is removed, store it in its relative position in a cardboard template of the crankcase halves. This will ensure ail bolts are Installed in their correct locations on reassembly.

8 Unscrew the twelve 8 mm lower crankcase (crankshaft journal) bolts evenly, a little at a time and in a reverse of the numerical tightening sequence, until they are finger-tight, then remove them, along with the washers (see illustration 21.4a or b, bolts numbered 1 to 12). Note: As each bolt /s removed, store it in its relative position in a cardboard template of the crankcase halves. This will ensure all bolts are installed in their correct locations on reassembly.

9 Carefully lift the lower crankcase half off the upper half, using a soft-faced hammer to tap around the joint to initially separate the halves if necessary (see illustration). Note: // fhe halves do not separate easily, make sure all fasteners have been removed. Do not try and separate the halves by levering against the crankcase mating surfaces as they are easily scored and will leak oil. Tap around the joint faces with a soft-faced mallet. The lower crankcase half will come away with the gearchange mechanism external components (if not already removed) and the selector drum and forks, leaving the crankshaft and transmission shafts in the upper crankcase half.

10 If required, remove the three locating dowels from the crankcase if they are loose (they could be in either crankcase half), noting their locations (see illustration). Similarly remove the two oil nozzles, noting which way up they fit.

11 Refer to Sections 22 to 30 for the removal, inspection and installation of the components housed within the crankcases.

Reassembly

12 Remove all traces of sealant from the crankcase mating surfaces.

13 Ensure that all components and their

bearings are in place in the upper and lower crankcase halves. If the transmission shafts have not been removed, check the condition of the output shaft oil seal on the left-hand end of the shaft and renew It if it is damaged or deteriorated (see illustration 28.4a); It is sound practice to renew this seal anyway. Apply some grease to the lips of the new seal on installation (see illustration 28.4b).

14 Generously lubricate the crankshaft and transmission shafts, particularly around the bearings, with clean engine oil, then use a rag soaked in high flash-point solvent to wipe over the mating surfaces of both crankcase halves to remove all traces of oil.

15 If removed, install the three locating dowels and the two oil nozzles in the upper crankcase half (see illustration 21.10). The oil nozzles must be fitted with the wider aperture facing out.

16 Apply a small amount of suitable sealant to the outer mating surface of the upper crankcase half.

Caution: Do not apply an excessive amount of sealant as it will ooze out when the case halves are assembled and may obstruct oil passages. Do not apply the sealant on or too close to any of the bearing inserts or surfaces.

17 Check again that all components are in position, particularly that the bearing shells are still correctly located in the lower crankcase half. Carefully install the lower crankcase half down onto the upper crankcase half, making sure each selector fork locates correctly in the groove in Its pinion, and the dowels all locate correctly into the lower crankcase half (see illus­tration 21.9).

18 Check that the lower crankcase half is correctly seated. Note: The crankcase halves should fit together without being forced. If the casings are not correctly seated, remove the lower crankcase half and investigate the problem. Do not attempt to pull them together using the crankcase bolts as the casing will crack and be ruined.

19 Clean the threads of the twelve 8 mm lower crankcase (crankshaft journal) bolts and insert them with their washers in their original locations (see illustration 21.4a or b). Secure all bolts finger-tight at first, then tighten them evenly and a little at a time in the correct numerical sequence to the torque setting specified at the beginning of the Chapter.

20 Clean the threads of the thirteen 6 mm lower crankcase bolts and insert them in their original locations (see illustration 21.4a or b). Secure all bolts finger-tight at first, then tighten them evenly a little at a time in the correct numerical sequence to the torque setting specified at the beginning of the Chapter.

21 Clean the threads of the single 8 mm lower crankcase bolt and insert it into the rear left-hand corner of the crankcase (see illustration 21.4a or b). Tighten the bolt to the specified torque.

22 Turn the engine over. Clean the threads of the six (J and К models) or seven (L, N and R models) 6 mm upper crankcase bolts and insert them in their original locations, not 2 forgetting the washers with the bolts whose locations are identified by a triangle cast into

the crankcase (see illustration 21.4a or b). Secure all bolts finger-tight at first, then tighten them evenly a little at a time in the numerical sequence to the torque setting specified at the beginning of the Chapter.

23 With all crankcase fasteners tightened, check that the crankshaft and transmission shafts rotate smoothly and easily. Check that the transmission shafts rotate freely and independently in neutral, then rotate the selector drum by hand and select each gear in turn whilst rotating the Input shaft. Check that all gears can be selected and that the shafts rotate freely in every gear. If there are any signs of undue stiffness, tight or rough spots, or of any other problem, the fault must be rectified before proceeding further.

24 Install the transmission input shaft bearing retainer plate onto the right-hand side of the crankcase. Apply a suitable non-permanent

2»40 Engine, clutch and transmission

thread-locking compound to the threads of the bolts and tighten them to the specified torque setting (see illustration 21.3). 25 Install all other removed assemblies in the reverse of the sequence given in Step 2.

I

22 Crankcase halves and cylinder bores - inspection and servicing

Crankcase halves

1 After the crankcases have been separated, remove the crankshaft, connecting rods, transmission shafts, selector drum and forks, and, if required, the oil pressure switch, neutral switch and cooling system union, referring to the relevant Sections of this Chapter, to Chapter 9 for the oil pressure switch and neutral switch, and to Chapter 3 for the coolant union. On J and К models, if required, unscrew the bolt securing the transmission input shaft needle bearing cage retainer in the bore in the crankcase, then remove the retainer and draw out the cage.

2 The crankcases should be cleaned thoroughly with new solvent and dried with compressed air. All oil passages should be blown out with compressed air.

3 All traces of old gasket sealant should be removed from the mating surfaces. Minor damage to the surfaces can be cleaned up with a fine sharpening stone or grindstone. Caution: Be very careful not to nick or gouge the crankcase mating surfaces or oil leaks will result. Check both crankcase halves very carefully for cracks and other damage.

4 Small cracks or holes in aluminium castings may be repaired with an epoxy resin adhesive as a temporary measure. Permanent repairs can only be effected by argon-arc welding, and only a specialist in this process is In a position to advise on the economy or practical aspect of such a repair. Note that there are. however, kits available for low temperature welding. If any damage is found that can't be repaired, renew the crankcase halves as a set.

5 Damaged threads can be economically reclaimed using a thread insert, which is easily fitted after drilling and re-tapping the affected thread. There are a few types of thread insert available, of varying quality and cost - consult your dealer for his recommendation.

6 Sheared studs or bolts can usually be removed with stud or screw extractors. A stud extractor should be used if the stud is above the surface. Otherwise use a screw extractor, which consists of a tapered, left thread screw of very hard steel. These are inserted into a hole pre-drilled centrally in the stud, and usually succeed in dislodging the most stubborn stud or screw.

IIWWJTl Refer to Tools and

HilUT

¹ Workshop Tips for details of installing a thread insert and using screw extractors.

7 Install all components and assemblies,
referring to the relevant Sections of this
Chapter and to Chapters 9 and 3, before
reassembling the crankcase halves.

Дата добавления: 2015-10-29