Removing the camshaft
Note. To remove the camshaft, remove the engine to prevent the tappets from falling into the engine.
Drain engine oil.
Remove the cylinder head cover and loosen the rocker arm adjusting nuts about 8 mm to release the push rods from the valve springs and move them away from the camshaft.
Remove the carburetor, turn the engine over and place it with the upper plane of the cylinder head on wooden linings.
Remove the crankshaft pulley.
Remove the camshaft drive cover and deflector.
Align the marks on the crankshaft and camshaft sprockets as shown in the photo, which will facilitate their subsequent installation.
Remove the camshaft timing chain tensioner.
Loosen the camshaft sprocket bolt.
Remove the sprocket and camshaft drive chain, having previously applied a colored alignment mark to the chain.
Remove the lock plate, noting its positions and remove the camshaft towards the front.
After removing the camshaft, access to the pushers appears, which, if necessary, can be replaced.
Bearing sleeves are available as spare parts only for camshafts with a journal diameter reduced by 0.5 mm (with processing allowance). Therefore, they must be deployed to the diameters of the camshaft journals. It is necessary to deploy three holes at once in a line using a combined reamer (see «Design and specifications»).
When pressing in new camshaft bearing bushes, make sure that their lubrication holes line up with the oil passages in the cylinder head.
Warning. After reaming the bores of the bearing bushings, carefully clean the oil channels from metal chips.
Installing the camshaft
Lubricate the camshaft journals with molybdenum disulphide grease and install it in place.
Install the camshaft retainer plate.
In the future, the installation of the shaft is carried out as indicated above in paragraph «Installing the camshaft drive».
Details of the gas distribution mechanism:
1 - camshaft;
2 - lock plate of the camshaft;
3 - bearing sleeve;
4 - crankshaft sprocket;
5 - camshaft sprocket;
6 - chain tensioner;
7 - camshaft drive circuit;
8 — laying of a cover of a drive of a camshaft;
9 — a cover of a drive of a camshaft;
10 - inspection hatch;
11 - sealing ring;
12 - inspection hatch;
13 - pusher;
14 - rocker bar;
15 - exhaust valve;
16 - inlet valve;
17 - rocker;
18 - cracker;
19 - valve spring plate;
20 - valve spring;
21 - rotary device of the exhaust valve;
22 - oil cap.
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