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XS360 (1976-1982)
Инструкция по эксплуатации Страница: 12

Yamaha XS360 (1976-1982) [12/34] Yamaha xs360 400

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Yamaha XS360 400 Cylinder and Piston Removal 1 Lift the cylinder a few inches off its seat and stuff a clean lint free rag or rags beneath the pistons This is to prevent any foreign matter or pieces of broken piston ring from falling into the crankcase when the cylinders are removed 2 Lift the cylinder straight up and free of the studs 3 With a needle nosed pliers remove the wrist pin circlips from the pistons Push out the piston wrist pins and remove the pistons from the rods 2 With a micrometer measure the height of each cam lobe and compare the measure ment with the specifications given in the chart at the end of this section 3 Measure the base circle of each cam lobe This measurement is taken in a plane perpendicular to the cam height measure ment through the camshaft centerline Refer to the specifications chart at the end of this section 4 Mount the camshaft in a set of v blocks and measure run out with a dial gauge If run out exceeds 0 03 mm 0 0012 in the cam should be replaced 5 Check the cam bearings for scoring and wear Check the journals as well Measure the journal diameters referring to the speci fications chart at the end of this section ROCKER ARMS AND SHAFTS Removing the piston wrist pin circlip Support the piston with one hand while pushing out the wrist pin to minimize chances of bending the rod Push the pin out with stead pressure Do not use an impact method If the wrist pins resist removal heat the piston crown gently and evenly with a propane torch until the pins can be easily pushed out Disgard the wrist pin circlips New circlips must be used on assembly 4 Mark each piston so that it can be in stalled in its original cylinder on reassembly Inspection CAMSHAFT 1 Check the cam lobes for flaking scor ing or blue discoloration and replace the cam if any of these signs of damage are 1 The rocker arms are fitted to the cylin der head cover To remove them remove the rocker arm shaft covers and grommets Thread an 8 mm screw into each shaft and pull it out If the shaft resists removal use a slide hammer to effect removal 2 Check the condition of the rocker arm bores and the corresponding areas of the shafts Note any blue discoloration which might be due to excessive heat or lack of lubricant Replace the rocker arms and shafts if this condition exists or if there are obvious signs of damage such as scoring 3 Check the cam contacting pad of each rocker arm for pitting or wear Replace the arm if wear is evident 4 Measure the inside diameter of the rocker arm bore and the outside diameter of the shaft Standard clearance is 0 016 0 054 mm 0 00063 0 00212 in If the clearance exceeds 0 1 mm 0 004 in replace the com ponents CYLINDER HEAD Measure cam lobe height A and base circle diameter B 1274 1 Clean any traces of head gasket material from the cylinder head mating surface Place a straight edge across the mating surface and check for warpage by attempting to slip feeler gauge blades between the head and straight edge Standard head warpage is about 0 05 mm 0 002 in and maximum al lowable warpage is 0 1 mm 0 004 in At this point the head should be milled to re store a flat mating surface 2 Use a wire brush fitting on a power drill to decarbonize the combustion chambers The valves should be left in place as this is done as it minimizes the chance of causing damage to the valve seats VALVE ASSEMBLY Before removing the valves check their seal ing ability by pouring a small quantity of gas oline into each port and allowing the head to sit for about five minutes If the valves are properly seating leakage into the combus tion chamber will be minimal 1 To remove the valves and install them properly a suitable C clamp is necessary Compress the valve springs and remove the split collars retainers springs seals and spring seats Inspect the valves guides springs and valve seats in the following man ner Keep each assembly separate so that every piece can be installed in its original location New valve seals must always be used on assembly 2 If considerable mileage has been cov ered the valve springs should be replaced as a matter of course Always replace valve springs as a set Measure the free length of each valve spring with a vernier caliper If any of the springs is more than 2 mm 0 08 in less than the standard free length given in the specifi cations chart at the end of this section the springs should all be replaced 3 Each valve must be free to move up and down in its guide with little resistance Any sticking or binding as the valve is moved in the guide will indicate that the valve stem or guide is in poor condition 4 Inspect the valve paying close atten tion to the edges of the valve head for pitting burnt or broken edges excessive carbon build up etc A certain amount of carbon and lead deposits on the valve face and the top of the exhaust valve are inevitable Heavy deposits should be carefully scraped off with a dull knife or a wire wheel and the valve finished up with very fine emery cloth Do not touch the valve seating area during these operations If the valve has burnt or broken edges it must be replaced 5 Check the end of the valve stem for in dented wear caused by the valve adjuster Although rare it may occur after long mile age Since an indentation here will make proper valve adjustments impossible the valve should be replaced NOTE The tips and edges of the valves are stellite coated Machining for any reason is not recommended In case of wear replace the valve 6 Carbon deposits should not extend too far up along the valve stem This would in dicate a worn or cracked valve guide 7 Wet oily deposits on the back of the valve head is indicative of a worn guide or bad seal Less severe wear to these compo nents show up as brown oil stains on the valve stem 8 Holding a valve in your fingers spin it while observing the head A wobble is indica tive of a bent valve If a dial gauge is avail able check the run out of the head Replace the valve if run out exceeds 0 03 mm 0 0012 in Run out is the total indicated dial gauge reading Attempt to rotate the valve by hand when it is fully inserted into the guide If the valve will not rotate easily or if it sticks as it is turned it is probably bent 9 Check valve to stem clearance and compare to the specification given Insert the valve in the guide holding it about in off

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