Stagger the ring end gaps as shown

rifle-cleaning brush to scrub out the oil passages. If available, blow the crank dry with compressed air, and also blow through the oilpassages. Check the camchain sprocket for wear or damage. If any of the teeth are excessively worn, chipped or broken, the crankshaft must be renewed. If wear or damage is found, also check the camchain, camchain guides andcamshaft sprockets (see Section 27). 6 Inspect the splines on the right-hand end of the shaft and ensure that the primary drive gear is a good fit on the splines. Inspect the taper and the slot in the left-hand end of the shaft for the alternator Woodruff key. Damage or wear that prevents either the primary drive gear or the alternator from being fitted

main bearing shells (see illustration).Remove the camchain from the crankshaft. Caution: With the crankshaft removed, do not try to remove the piston/connecting rod assemblies from the bottom of the cylinder bore. The piston will not pass the crankcase main bearing webs. If the piston is pulled right to the bottom of the bore the oil control ring will expand and lock the piston in position. If this happens it is likely the ring will be broken.

4 The main bearing shells can be removed
from the crankcase halves by pushing their
centres to the side, then lifting them out (see
illustration).Keep the shells in order.

Inspection

5 Clean the crankshaft with solvent, using a

25.3 Lift the crankshaft and camchain out 25.4 Push the shells out, don't lever them together

Engine, clutch and transmission 2»43

25.6a Inspect the primary gear splines...

securely will require a new crankshaft (seeillustrations).

7 Refer to Section 21 and examine the main bearing shells. If they are scored, badly scuffed or appear to have been seized, new shells must be installed. Always renew the main bearing shells as a set. If they are badly damaged, check the corresponding crankshaft journals. Evidence of extreme heat, suchas discoloration, indicates that lubrication failure has occurred. Be sure to thoroughly check the oil pump and pressure relief valve as well as all oil holes and passages before reassembling the engine.

8 Give the crankshaft journals a close visual examination, paying particular attention where damaged bearings have been discovered. If the journals are scored or pitted in any way a new crankshaft will be required. Undersize main bearing shells are not available, precluding the option of re-grinding the crankshaft.

9 Place the crankshaft on V-blocks and check the runout at the main bearing journals using a dial gauge. Compare the reading to the maximum specified at the beginning of this Chapter. If the runout exceeds the limit, the crankshaft must be renewed.

Oil clearance check

10The crankshaft main bearing oil
clearances should be checked before the
engine is reassembled even if the bearing
shells and the crankshaft journals show no
apparent sign of wear. Bearing oil clearance is
measured with a product called Plastigauge.

Date: 2016-01-14; view: 518

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