Inspection and servicing
1. After the crankcases have been separated, remove the oil pump, and on XRV models the oil distributor, the crankshaft and connecting rods, transmission shafts, selector drum and forks, neutral switch and oil pressure switch, referring to the relevant Sections of this Chapter, and to Chapter 9 for the neutral and oil pressure switches. Refer to Section 30 and to Tools and Workshop Tips in the Reference Section for checks and information on the transmission shaft bearings. Refer to Sections 26 and 27 and to Tools and Workshop Tips in the Reference Section for checks and information on the crankshaft main bearings.
2. If not already done (Section 16), prise the oil jets out of the crankcases using a small screwdriver (see illustration 16.13a) - take care not to damage them. Remove the O-rings and discard them (see illustration 16.13b). Clean the jets with solvenl and blow them through with compressed air if available.
3. Unscrew the bolt securing the cam chain tensioner set plate to the right-hand crankcase half and remove the plate, noting how it fits (see illustration).
24.3. Unscrew the bolt (arrowed) and remove the plate
4. Unscrew the bolt(s) securing the oil seal retainer plate to the left-hand half of the crankcase and remove the plate, noting how it fits (see illustration 23.3). Check the condition of the oil seals and replace them with new ones if there any signs of damage, deformation or oil leakage (see illustration). Lever out the old seal with a screwdriver, then press or drive the new seal in using a suitable socket or seal driver (see illustrations).
24.4a. Check the transmission output shaft oil seal (A) and the gearchange shaft oil seal (B)
24.4b. Lever out the old seal...
24.4c ...and press or drive the new one into place
5. Remove all traces of old gasket sealant 2 from the mating surfaces. Clean up minor damage to the surfaces with a fine sharpening stone or grindstone.
6. Clean the crankcases thoroughly with new solvent and dry them with compressed air. Blow out all oil passages with compressed air.
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.
7. Check that all the cylinder studs are tight in the crankcase halves. If any are loose, remove them, then clean their threads and apply a suitable non-permanent thread locking compound and tighten them to the torque setting specified at the beginning of the Chapter. When torquing the studs, be sure to distinguish correctly between the 8 mm stud and the 10 mm studs.
8. Small cracks or holes in aluminium castings can be repaired with an epoxy resin adhesive as a temporary measure. Permanent repairs can only be done 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. If any damage is found that can't be repaired, replace the crankcase halves as a set.
9. Damaged threads can be economically reclaimed using a diamond section wire insert, for example of the Heli-Coil type (though there are other makes), which is easily fitted after drilling and re-tapping the affected thread.
10. Sheared studs or screws can usually be removed with extractors, which consist of a tapered, left-hand thread screw of very hard steel. These are inserted into a pre-drilled hole in the stud, and usually succeed in dislodging the most stubborn stud or screw. If a stud has sheared above its bore line, it can be removed using a conventional stud extractor which avoids the need for drilling.
Refer to Tools and Workshop Tips for details of installing a thread insert and using screw extractors.
11. Install all components and assemblies, referring to the Steps above and the relevant Sections of this and the other Chapters, before reassembling the crankcase halves. Fit new O-rings onto the oil jets (see illustration 16.13b) before installing them (see illustration 16.13c).
Crankcase renewal
12. If new crankcases are required, replacements are supplied on a selected fit according to the crankshaft main journal size - this is so that the crankcases are supplied with the correct size main bearings. Code numbers and letters stamped on the crankshaft and crankcase are used to identify the correct replacement.
13. Each crankshaft main bearing journal size number is stamped on the outside crankshaft web adjacent to the journal, and will be either a 1 or a 2 (see illustration). The corresponding mam bearing size letter is stamped into the appropriate crankcase half adjacent to the bearing housing and will be either an A or a B (see illustration). If the crankshaft journal size is coded 1, the corresponding crankcase main bearing must be coded A. If the crankshaft journal size is coded 2, the corresponding crankcase main bearing must be coded B.
24.13a. Main bearing journal size numbers (A), big-end bearing size letters (B)
24.13b. Main bearing size letter (arrowed)