Contents: Examination ↡ Replacement ↡
Examination
1. Remove the air cleaner as described in Chapter 4.
2. Remove the camshaft cover as described in paragraph 4.
3. Using a socket wrench on the crankshaft pulley/vibration damper hub bolt, turn the crankshaft to gradually expose the entire chain to the camshaft sprocket.
4. The chain should be replaced if the sprocket or chain is worn out (manifests itself in increased longitudinal play between the links and increased noise during operation). It is recommended to replace the chains every time the engine is disassembled. Note that the rollers on a worn chain may be worn out. To avoid problems in the future, if there is any doubt about the condition of the chain, replace it.
Replacement
Note: Removing the chain using this method requires using a portable electric grinder to cut one of the chain links. Before you begin, make sure you have access to this tool and a new chain and connecting link.
5. Disconnect the negative battery terminal.
6. Follow the steps described in steps 1 and 2.
7. Remove the spark plugs as described in Chapter 1A.
8. Remove the chain tensioner as described in paragraph 8.
9. Cover the camshaft and the portion of the chain not covered by the casing with clean rags. Do not cover the top of the camshaft sprocket with rags.
10. Using a grinder, file down the chain link protrusion on the top of the sprocket - be careful not to damage the sprocket.
11. Remove the chain link plate and push the link to the back of the chain.
12. Collect the rags, taking care to prevent the shavings from falling down into the chain cover.
13. Using a new link, connect one end of the new chain to the end of the old chain so that when you turn the crankshaft clockwise, the new chain goes down around the sprockets, then up the other side. Fit the link to the back of the sprocket and make sure the link is securely in place - do not fit the link plate to secure the link at this stage.
14. After this, it is necessary to pass the new chain through the sprockets and guides. During this procedure, the following points should be observed: (see fig. 7.14).
- a) Maintain chain tension so that the chain links do not jump off the camshaft sprocket. Otherwise, the valve timing will be disturbed.
- b) Pull the old chain upwards to prevent it from slipping off the crankshaft sprocket or becoming skewed in the guides.
Fig. 7.14. Maintain tension on the new chain as you thread it around the sprockets and guides
15. Using a suitable socket wrench, slowly turn the crankshaft pulley hub bolt clockwise, following the recommendations given in the previous step.
16. When the end of the new chain appears, remove the link (checking that the tension of the new chain has not decreased and that the chain links remain aligned with the sprockets) and disconnect the new chain from the old one. Remove the old chain.
17. Place the new chain on the camshaft sprocket, then connect the two ends of the chain with the connecting link inserted into the back of the sprocket (see fig. 7.17).
Fig. 7.17. Installing the camshaft drive chain link (shown by arrow) from the back of the chain
Tip: Temporarily secure the ends of the new chain to the sprocket using a rope or string threaded through the holes in the sprocket and around the chain.
18. Install the link plate and secure the link by flattening the link pins. A special device is provided for this purpose, however, satisfactory results can be achieved using a hammer and a block of metal (or the second hammer), to support the back of the chain. Be careful not to damage the chain or sprocket.
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19. Check that the link is securely fastened without any metal burrs or chips.
20. Install the chain tensioner as described in paragraph 8.
21. Turn the crankshaft clockwise to set the piston of the 1st cylinder to the TDC position, checking that the timing marks of the crankshaft and camshaft are correctly aligned, as described in paragraph 3.
22. It is possible that during this operation the chain will shift by one tooth of the camshaft sprocket. In this case, the valve timing can be adjusted by removing the sprocket (see paragraph 8) and changing the position of the camshaft and sprocket by one tooth in relation to the chain.
23. Install the spark plugs.
24. Install the camshaft cover as described in paragraph 4, then install the air cleaner.
25. Connect the negative battery terminal.