Manual - Chapter 1 Engine

29. Reassembling the engine unit: refitting the output/balancer shaft and crankcase lower section

  1. Check that the front bearing inner sleeve is secured in place by its circlip and fit the larger circlip, followed by the needle bearing over it. Lubricate both bearings.
  2. On 75 models fit the balancer shaft to its bearing recesses ensuring that the dot or V mark aligns exactly with the straight line on the crankshaft gear, as noted on removal. and that the marks remain in alignment as the balancer shaft bearings are pressed into place. Ensure that the rear bearing shoulder fits fully into its groove and that the front bearing locating circlip fits into its groove with its open end aligned on each side of the crankcase mating surface (ie so that the circlip compresses easily as the castings are clamped together).
  3. On early 100 models - identified by the rear bearing having a thin (1.75 mm/0.07 in) locating circlip - thoroughly clean and degrease the rear bearing circlip and outside edge and the bearing recess, especially the circlip groove. Apply a thin coat of Loctite 273 or Three Bond 1110 B adhesive to the groove and refit the shaft. Press both bearings and circlips into their respective housings and grooves, ensuring that the circlip open ends are aligned on each side of the crankcase mating surface (ie so that the circlip compresses easily as the castings are clamped together).
  4. On late 100 models - identified by the rear bearing having a thick (3.52 mm/0.14 in) locating shoulder at the outer race rear end - install the output shaft as described in paragraph 2 above, except that there are no timing marks to set.
  5. On all models, check that the output/balancer shaft bearings are fully seated and check that it is free to rotate with the crankshaft. On 75 models check the timing marks again after one or two revolutions.
  6. Install the two locating dowels in their recesses next to each bearing and place two new a-rings in the grooves around the oil and coolant passages.
  7. Lubricate the output/balancer shaft bearings and gear teeth, check that the mating surfaces are absolutely clean, undamaged and degreased (wipe them over with a rag soaked in a suitable high flash-point solvent) and apply a thin coat of Loctite 574 or Three Bond 1207 B jointing compound following the manufacturer's instructions.
  8. Fit the crankcase lower section and its retaining bolts or screws. At first tighten evenly the four 'inside' bolts by hand until the lower section is seated securely, then tighten first the rear two hexagonheaded bolts to their specified torque setting, followed by the front two Allen-headed bolts or screws to their (lower) torque setting. Finally refit and tighten evenly the 'outside' Allen bolts or screws to their specified torque setting.
  9. Check again that the output/balancer shaft is free to rotate easily with no traces of stiffness.
  10. Once the crankcase lower section is secured the output shaft rear seal may be refitted. Clean the seal outer edge, the shaft and its housing then apply a thin smear of grease to the housing, the seal outer edge and its sealing lips. Position the seal so that it is absolutely square to the housing and tap it in, until it is flush with the housing, using a hammer and a tubular drift such as a socket spanner which bears only on the seal's hard outer edge.

Fig 1.9 Crankshaft / Balancer shaft timing marks - 75 model

29.1 Fit larger circlip and bearing to output shaft front end

29.4a Ensure output shaft rear bearing is settled securely in its locating groove

29.4b Position open end of front bearing locating circlip on each side of mating surface, as shown

29.6a Check two locating dowels (arrowed) are pressed into locations next to bearings ...

29.6b ... and fit new O-rings to oil and coolant passages

29.7 Apply a thin coat of sealant to mating surface as described in text

29.8a Tighten to specified torque wrench settings, the output shaft rear bolts ...

29.8b ... followed by front bolts or screws

29.8c ... and bolts or screws around matting surface edge

29.10 Fit output shaft rear seal as described in text