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Main bearing shell selection

21New bearing shells for the main bearings are supplied on a selected fit basis. Code letters and numbers marked on the crankshaft webs and the left-hand side of the upper crankcase half are used to identify the correct new bearings. The crankshaft main bearing journal size codes are marked on the four crankshaft webs and will be either a 1, 2, or 3 (see illustration).The corresponding main bearing housing size codes are stamped into the upper crankcase half and will be either an A, B or C (see illustration).The left-hand letter corresponds to the left-hand journal, and so on from left to right respectively.

22A range of bearing shells are available. To select the correct bearing for a particular journal, using the table below cross-refer the main bearing journal size code (marked on the adjacent crank web) with the main bearing housing size code (stamped on the crankcase) to determine the colour code of the bearing required. For example, if the journal code is 1, and the housing code is B, then the bearing required is Green. The colour is marked on the side of the shell (see illustration 22.21).


A Crankshaft main bearing journal size codes

Installation

23Clean the backs of the bearing shells and the bearing seats in both crankcase halves. If new shells are being fitted, ensure that all traces of protective grease are cleaned off using paraffin (kerosene). Wipe the shells and crankcase halves dry with a lint-free cloth. Make sure all the oil passages and holes are clear, and blow them through with compressed air if it is available.

24 Press the bearing shells into their seats, aligning the tab on each shell with the groove in the crankcase (see illustration 25.12).Make sure the bearings are seated correctly and take care not to touch any shell's bearing surface with your fingers. Lubricate each shell with a50/50 mixture of molybdenum disulphide grease and clean engine oil.

25Fit the camchain over the crankshaft sprocket and lower the crankshaft into position in the upper crankcase, making sure all bearings remain in place.

26 Fit the connecting rods onto thecrankshaft (see Section 22).

27 Reassemble the crankcase halves (see Section 20).

^ ^ ^

26 Balancer shaft and bearings jfe>

- removal, inspection and

installation

Note:To remove the balancer shaft the engine must be removed from the frame.

Removal

1Remove the engine from the frame (see Section 5) and separate the crankcase halves (see Section 20).

2 Turn the balancer shaft so that it can be lifted out of the upper crankcase half without disturbing the crankshaft (see illustration).


B Main bearing housing size codes

Take care not to dislodge the bearing shells.

3 The balancer shaft bearing shells can be
removed from the crankcase halves by
pushing their centres to the side, then lifting
them out. Keep the shells in order.

Inspection


26.2 Lift the balancer shaft (arrowed) out without disturbing the crankshaft

4 Clean the balancer shaft with solvent. If available, blow through the oil passages with compressed air. Note:Thorough cleaning of the crankcase oil passages can only be achieved with both the balancer shaft and crankshaft removed (see section 25).



5 Inspect the splines on the right-hand end of the shaft and ensure that the drive gear is a good fit on the splines. Damage or wear that prevents the drive gear from being fitted securely will require a new balancer shaft.

6 Refer to Section 21 and examine the balancer shaft bearing shells. If they are scored, badly scuffed or appear to have been seized, new shells must be installed. Always renew the bearing shells as a set. If they are badly damaged, check the corresponding balancer shaft journals. Evidence of extreme heat, such as 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.

7 Give the balancer shaft 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 balancer shaft will be required,

8 No specifications are available for the


Engine, clutch and transmission 2*45






V^

 

26.10 Lubricate the bearing shells ,

balancer shaft journals or the bearing shells. Even if both appear to be in perfect condition, if the engine has covered a high mileage and has been stripped for overhaul, install new bearing shells. Always renew all of the shells at the same time.

Installation

9 Clean the backs of the bearing shells and
the bearing seats in both crankcase halves. If
new shells are being fitted, ensure that all
traces of protective grease are cleaned off
using paraffin (kerosene). Wipe the shells and
crankcase halves dry with a lint-free cloth.
Make sure all the oil passages and holes are
clear, and blow them through with
compressed air if it is available.

10Press the bearing shells into their seats, aligning the tab on each shell with the groove in the crankcase (see illustration 25.12).Make sure the bearings are seated correctly and take care not to touch any shell's bearing surface with your fingers. Lubricate each shell with a 50/50 mixture of molybdenum disulphide grease and clean engine oil (see illustration).

11Lower the balancer shaft into position in the upper crankcase, making sure all bearings remain in place (see illustration).

12Reassemble the crankcase halves (see Section 20).

I

27 Camchain and guide/ tensioner blades - removal, inspection and installation

Note:To remove the camchain and guides the engine must be removed from the frame.

Removal

1 Remove the engine from the frame (see Section 5), remove the cylinder head (see Section 10) and separate the crankcase halves (see Section 20).

2 Remove the crankshaft (see Section 25) and lift the camchain off the shaft.

3 Lift the front guide blade (orange) and rear tensioner blade (black) out of the upper crankcase half. Note how they fit with the bowed face bearing against the camchain and their lower ends resting in slots in the upper crankcase half (see illustrations).

Inspection

4Check the camchain for signs of wear such as highly polished surfaces on the sideplates. Lay the chain on the work surface and compress and stretch sections of the chain to check for wear between the links. Flex the chain and check for binding between links. If the chain is worn in any respect, it must be renewed.

5 Check the camchain for signs of damage, and if any is found, inspect the sprockets on the crankshaft and the camshafts (see illustration).Renew the camchain together with the damaged components.


27.3a Note location (arrowed) of front guide blade...

6No specifications are available for service limits for the camchain. If the engine has covered a high mileage and has been stripped for overhaul it is advisable to renew the chain.

7 Inspect the camchain guide blade and tensioner blade, including the upper guide on the cylinder head, for grooves, cracking and other damage. Check the tensioner blade where it makes contact with the camchain tensioner plunger. Renew the guides/blades if any wear is found.

Installation

27.5 Inspect crankshaft camchain sprocket for wear and damage

8Install the front and rear camchain blades (see Step 3). Fit the camchain over the crankshaft sprocket and lower the crankshaft into position in the upper crankcase.

9 Ensure the camchain is laying correctly overthe crankshaft sprocket. Pull the camchain through the engine block and secure it with a length of wire to prevent it



Date: 2016-01-14; view: 675


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