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Disassembly and maintenance of cylinder head assembly

1. Cylinder head assembly drawing . For this drawing please see the bottom of this document

For a key to these diagrams please visit the bottom of this document.

For the key to these diagrams see the end of this document

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Summary of Contents for NC450

Page 1: ...age 131 GPX 450 FSE Engine manual ZS194MQ NC450 send move machine dimension build handbook Chongqing Zongshen Engine Manufacturing Co Ltd Prepare Proofread Review Approve Repair of cylinder head assembly ...

Page 2: ...or valve seal Incorrect gas timing Broken valve spring 2 cylinder head The spark plug is not tightly connected to the cylinder head Damaged cylinder head gasket Cracks or blisters in the cylinder head 3 Cylinders Pistons Piston Rings Excessive or broken piston ring clearance Cylinder block Exhaust with black smoke 1 valve guide wear 2 Oil shield leaking or damaged 3 Cylinder head gasket leakage 4 ...

Page 3: ...Cylinder head assembly drawing For this drawing please see the bottom of this document For a key to these diagrams please visit the bottom of this document For the key to these diagrams see the end of this document 1 1 12 13 12 3 14 1 5 16 17 4 5 6 7 8 9 1 7 8 9 1 6 ...

Page 4: ...the tensioner Then remove the tensioner assembly and the tensioner gasket 2 Turn the timing driven sprocket to the engine timing position Arrow mark of timing driven sprocket and cylinder head timing mark align 3 Remove the bolt M6 16 and the flat washer and remove the NC 450 pressure reducing valve throw block combination 4 Remove 2 bolts M6 10 and take off the timing driven chain Tensioner combi...

Page 5: ...remove the NC450 camshaft pressure plate 2 Remove the camshaft 3 Remove the two NC250 rocker shafts on the cylinder head cover for positioning Bolt M14 1 4 Remove 2 bolts M6 18 and 2 flat washers lock up 4 Remove the intake and exhaust rocker arm shafts and remove the intake and exhaust rocker arms 5 Press down the valve spring with the valve remover and remove the valve lock clip then loosen the ...

Page 6: ... of the contact surface 1 5mm Notice If the valve contact surface is rough the abrasion is uneven or the contact with the valve seat is abnormal and the sealing performance cannot be guaranteed the valve should be replaced 3 Check whether the valve spring is abnormally worn and the measurement is free length Repair limit Outer spring 39 75m Inner spring 36 85mm Inspection of rocker arm and rocker ...

Page 7: ...nspection of the cylinder head 1 Check whether the sealing of the cylinder head is good If the sealing of the cylinder head is poor a new cylinder head or valve should be replaced 2 Check whether the cylinder head is deformed and check the flatness of the cylinder head with a knife edge ruler and a feeler gauge 燃烧室检漏测试充气 0 3Mpa 泄漏量 6000pa 10 秒检测参数充气时间 5S 平衡时间 3S 检测时间 2S 放气时间 0 5S 检压上限 ...

Page 8: ...ce 5 Carry out the air tightness test on the assembled cylinder head combination If the air tightness test of the cylinder head combination is qualified the next step can be performed assemble according to the cylinder head composition diagram 6 Take the assembled camshaft parts apply grease on the surface of the small journal assemble it at the position of the camshaft hole of the cylinder head t...

Page 9: ... assemble it at the designated threaded hole position of the cylinder head Notice 1 When installing the rocker arm shaft the side of the rocker arm shaft with the trimmed edge should face the top of the cylinder head cover 2 After the cylinder head cover is installed turn the rocker arm The rocker arm should rotate flexibly without sticking Installation of the cylinder head 1 Remove the old cylind...

Page 10: ...timing adjustment method 1 Remove the large viewing hole cover of the left front cover and the bolts of the NC250 rocker shaft positioning plate 2 Rotate the NC250 magneto lock nut with a special tool and at the same time pass the bolt hole of the rocker shaft positioning plate on the left front cover Observe whether the timing mark one on the magneto rotor is aligned with the timing mark on the l...

Page 11: ... pressure reducing valve return spring and throw the pressure reducing valve block The combination and pressure reducing valve return spring is assembled on the camshaft through the timing driven sprocket take the bolt M6 16 and put it into the flat washer install it into the corresponding threaded hole of the camshaft and fasten it Tightening torque 11 to 13N m 7 Adjust the gap between the intake...

Page 12: ...over bolt buffer washer 3 and assemble them on the designated position of the NC450 cylinder head cover 2 2 Take 2 pieces of NC450 cylinder head cover fixing bolts 4 and 2 pieces of NC450 cylinder head cover fixing bolts 5 assemble the NC450 cylinder head cover 2 on the cylinder head and fasten them Tightening torque 11 13N m ...

Page 13: ...block into the oil passage hole Maintenance parameters of each component project Standard value mm Maintenance limit mm cylinder Cylinder bore φ94 5 φ94 52 φ94 528 Out of roundness 0 05 0 01 Cylinder surface flatness 0 03 0 05 piston piston ring live plugged Piston outside diameter φ94 45 φ94 46 φ94 43 Piston pin hole inner diameter φ20 001 φ20 006 φ20 015 Piston pin and piston pin hole clearance ...

Page 14: ...ton 2 NC450 piston pin retaining ring 3 NC450 piston ring assembly 4 NC450 piston pin 5 NC450 cylinder block parts 6 NC450 cylinder block gasket 7 Cylindrical pin φ6 12 8 NC450 chain guide plate combination 9 NC450 timing chain combination ...

Page 15: ...emaining gasket on the cylinder surface Cylinder block inspection 1 Check whether the cylinder block is worn or damaged 2 When measuring the inner diameter of the cylinder three positions should be measured namely the top middle and bottom of the piston stroke and two directions at right angles to each other should be measured during measurement Maintenance limit φ94 528mm boltM6 25 chain guide ...

Page 16: ... piston rings 1 Remove the piston ring 2 Measure the gap between the piston ring and the groove of the piston ring and the maintenance limit value The first ring 0 08mm Second Ring 0 08 mm Oil ring 0 08 mm 3 Check whether the piston is worn or cracked and whether the groove of the piston ring is worn 4 Insert the piston ring into the cylinder and then measure the closed gap of the piston ring Repa...

Page 17: ...Page 1731 ...

Page 18: ...n Ring Installation 1 Thoroughly clean the groove of the piston ring 2 Install the piston ring Notice 1 During installation the piston and piston rings should be protected from damage 2 When installing the piston ring do not install the first ring and the second ring wrongly The marked side of the first and second rings faces the top of the piston 3 After installation the piston ring should rotate...

Page 19: ...Page 1931 installed first and then the side guide rails should be installed ...

Page 20: ... Do not let the piston pin retaining ring fall into the crankcase Installation of the cylinder block 1 Install cylinder block positioning pins and new cylinder block gaskets 2 Apply a layer of oil evenly on the surface of the cylinder block piston and piston ring 3 First stagger the openings between the piston rings by 120 and then gently assemble the cylinder block in place 4 Assemble the chain g...

Page 21: ...double gear and starter motor 21 Installation of clutch 10 Inspection of water pump impeller 22 Installation of starter motor 11 Inspection of clutch 23 Installation of right crankcase cover 12 Inspection of active teeth Maintenance notice instruction After removal of the right crankcase cover removal installation and maintenance of the clutch oil pump and shifting mechanism can be carried out wit...

Page 22: ...e out the fine filter part 2 remove the oil filter cover 3 of the left and right boxes take out the oil filter combination 4 in the box wait for the oil in the box to run out and then disassemble the machine When removing the oil filter cover pay attention to whether the O rings 5 and 7 of the oil filter cover are damaged 2 Remove the connecting screws and take off the right crankcase cover Note W...

Page 23: ...push rod in the center hole of the main shaft Dismantling of driving gear super detachment and starting large gear 1 Remove the drive gear lock nut and the lock nut washer 2 Remove the driving gear super separate and start the big gear Notice When removing the starter gear assembly remove the washer under the starter gear together and keep the washer in a safe place Removal of the right body oil p...

Page 24: ...ould be properly kept to avoid loss Disassembly of the double gear First remove the double gear shaft then remove the first double gear and the second double gear Removal of starter motor Remove the starter motor fastening screws M6 25 and take off the starter motor Removal of the gearshift mechanism 1 Remove the M6 35 fixing screws of the five star board and remove the five star board 2 Remove th...

Page 25: ...il seal 1 Check whether the water pump impeller has cracks and whether the inserts of the water pump impeller are loose If the above phenomenon occurs a new water pump impeller should be replaced 2 Check whether the water seal components and oil seals are broken and check whether the wear of the water pump shaft is abnormal and whether there is bending If so you need to replace the new water seal ...

Page 26: ... Inspection of clutch active friction plate 1 If there are scratches or fading marks on the clutch friction plate it should be replaced Measure the thickness of each clutch lining Maintenance limit 2 85mm 2 Check whether the surface of the clutch disc is twisted and use a feeler gauge flatness when checking Service limit 0 14 mm 3 Check the clearance between the clutch cover and the friction plate...

Page 27: ...worn or damaged and whether the wedge spring is stretched or broken Inspection of the right body oil pump 1 Check whether the inner and outer rotors of the oil pump are worn or damaged If the wear and damage are serious you need to replace the new oil pump rotor assembly 2 Check whether the combination of the oil pump bridge gear and the oil pump gear is cracked and if so it needs to be replaced w...

Page 28: ...nd put it into the corresponding position note the shift arm return spring is clamped into the right shift arm positioning bolt 4 Test whether the shifting is correct and smooth 5 Take the oil seal 8 of the LY350 reverse gear shift drum and install it on the oil seal hole of the left shift arm with a tooling Assembly of the right body oil pump 1 Pass the oil pump shaft 1 through the corresponding ...

Page 29: ...or the marked surfaces of the inner and outer rotors should face the same direction 2 Tightening torque of oil pump cover bolts 7 9 Nm 3 After the cover plate is assembled make sure that the oil pump shaft rotates flexibly 5 Install the oil pump bridge gear washer 9 on the oil pump bridge gear shaft install the oil pump bridge gear 10 on the oil pump bridge gear shaft and then install the oil pump...

Page 30: ...ving teeth install it on the right crank and tighten it Tightening torque 115 125 N m Thread fastener name Loctite 263 Installation of the clutch 1 Install the clutch cover washer 19 needle bearing 20 clutch cover 21 and clutch center sleeve washer 22 on the main shaft NOTE Apply oil evenly to the clutch needles 2 First install the clutch center sleeve assembly 23 and the clutch lock nut washer 24...

Page 31: ... end of the starter motor assemble the starter motor in place and fasten it with 2 bolts M6 25 the tightening torque is 11 13N m Installation of the right crankcase cover 1 Install the two positioning pins 1 into the positioning pin holes of the case body remove the old right crankcase gasket 2 install the new gasket assemble the right crankcase cover in place and use 11 bolts M6 35 tightening tig...

Page 32: ...ation of left crankcase cover Maintenance notice The removal and installation of the magneto and the balance main and driven gears described in this section can be completed only by removing the left crankcase cover without removing the engine Removal of left crankcase cover Remove the fastening bolts of the left front cover and take off the left crankcase cover Disassembly of the magneto stator 1...

Page 33: ...rocket 3 and balance drive gear 4 3 Remove the balance driven gear lock nut 5 and the CB125 clutch disc washer 6 4 Remove the balance gear driven wheel 7 the NC250 crankshaft sleeve and the balance shaft flat key Removal of the left body oil pump 1 Remove the 3 GB T16674 small plate bolts M5 1 2 that fasten the left oil pump cover plate 2 Remove the oil pump cover remove the left oil pump rotor as...

Page 34: ...mp shaft and then install the left body oil pump 2 into the corresponding hole of the left body 2 Fasten the left cover plate 4 of the oil pump with 3 bolts M5 1 2 3 Notice 1 When installing the oil pump rotor the marked surfaces of the inner and outer rotors should face the same direction 2 Tightening torque of the bolts of the left oil pump cover plate 7 9N m 3 After tightening check whether the...

Page 35: ...ft timing driving sprocket 9 and the balance driven gear assembly 7 respectively and lock them on the balance shaft Nut M24 1 12 Clutch lock nut M16 1 13 Apply 3 4 threads of thread tightening glue then install it on the crankshaft and balance shaft and fasten it The tightening torque of the balance driven gear lock nut 80 90N m and the tightening torque of the balance driven gear lock nut 115 125...

Page 36: ...ver 1 Remove the old gasket 21 and install a new gasket 2 Install the two positioning pins 22 on the box body 3 Assemble the left crankcase cover 23 in place and fasten it with 2 M6 35 bolts 24 and 6 M6 30 bolts 25 Tightening torque 11 13 N m Note One of the M6 30 bolts 26 is coated with Sanhe glue on the disk and inserted into the flat washer 27 and inserted into the corresponding position as sho...

Page 37: ...f other parts of the engine should be carried out before the crankcase is separated Work before crankcase separation Disassembly of the cylinder head Cylinder Piston Removal Dismantling of clutch oil pump shifting mechanism and balance teeth Disassembly of the magneto Maintenance parameters of each component project Standard value mm Maintenance limit mm shift fork Inner diameter of countershaft r...

Page 38: ...haft shift fork shaft shift fork shift drum and main and countershaft components from the box Notice When taking out the main and auxiliary shaft assemblies make sure that no parts are left behind crankshaft inspection Use a thickness gauge to measure the backlash at the big end of the connecting rod Service limit 0 7 mm Inspection of left and right case bearings 1 Check whether all the bearings o...

Page 39: ...e excessive or abnormal wear and check whether the collars between the gears are deformed or fallen off Inspection of oil filter parts and oil filter 1 Check the cleanliness of the oil filter parts and oil filter screen rinse the oil filter parts and oil filter screen with poor cleanliness with clean gasoline 2 Check whether the oil filter parts and oil filter are damaged if there is damage replac...

Page 40: ... then fit the other end of the shift fork into the corresponding slot of the shift drum and finally install the shift fork shafts 8 and 9 to the corresponding shift fork middle Notice The long fork shaft passes through the forks marked R and L and the short fork shaft passes through the forks marked C Close the box 1 Apply a layer of sealant evenly on the box fitting surface of the right box insta...

Page 41: ...ue 11 to 13 N m Assembly of the oil filter 1 Assembly of the left body oil filter Take 1 oil filter assembly 1 apply a small amount of oil to its O ring and install it into the corresponding oil filter hole Install the oil filter cover O ring 2 on the oil filter cover apply an appropriate amount of grease to the inner hole of the oil filter cover 3 and fasten it on the box body Tightening torque 1...

Page 42: ...6674 Set the small plate bolt M6 16 into the corresponding hole of the fine filter cover and fasten it in the corresponding position of the right body Tightening torque 7 to 9 N m 1 Camshaft assembly 2 NC450 camshaft pressure plate 3 Screw M6 12 4 NC450 intake rocker arm combination 5 NC450 exhaust rocker arm combination 6 NC250 rocker shaft positioning bolt 7 O ring 8 NC450 valve rocker arm shaft...

Page 43: ...Page 4331 14 NC450 pressure reducing valve return torsion spring 15 NC450 camshaft pressure reducing valve block combination 16 Flat washer 17 Bolt M6 16 1 2 3 ...

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