Haynes Yamaha Xv V Twins Manual
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3A-6 Chapter 3 Part A Fuel and exhaust systems (XV535 models) 6.8 If this wiring harness obstructs removal, detach it from its clip (arrow) and move it out of the way 6.9 Loosen the clamp and pull the fuel line off the fitting 6.10a Loosen the clamping band screws on the air cleaner joints ... 6.10b ... insert a flat-bladed screwdriver between the joint and carburetor (arrow) and push the joint up into the air cleaner cavity 6.11 a Loosen the clamping band screws (upper arrows); an alternative method is to unbolt the intake joints from the cylinder head (lower arrows) 6.11 b Work the carburetors free of the intake joints (if theyre still bolted to the engine)... 6.11c ... and remove the carburetors from the left side of the bike 6.13a Remove the Allen bolts (arrows) 6.13b ... and take the intake joints off; replace the O-rings (arrow) 8 The wiring harness on the right side may interfere with removal (see illustration). If it does, free it from its clip and move it aside. On 1991 and later UK models, disconnect the carburetor heater unit valve from each carburetor. 9 Disconnect the fuel inlet line from the carburetor fitting (see illustration). 10 Loosen the clamp screws and disconnect the air cleaner joints from the carburetors (see illustrations). Push the joints up off the carburetors with a screwdriver (theyll fold into the air cleaner cavity in the frame). 11 Loosen the screws on the carburetor joints (see illustration). Work the carburetors free of the joints and lift them out (see
Chapter 3 Part A Fuel and exhaust systems (XV535 models) 3A-7 7.1 Carburetors (XV535 models) - exploded view 1 Jet needle assembly 2 Vacuum piston 3 Main nozzle 4 O-ring 5 No. 2 pilot air jet 6 No. 1 pilot air jet 7 Drain screw 8 Float 9 Needle valve 10 Choke plunger assembly 11 Coasting enricher diaphragm 12 Main jet 13 Main bleed pipe 14 Pilot jet 15 Throttle stop screw 7.2a Remove the float chamber cover screws and take off the cover ... illustrations). Note: You can also unbolt the joints from the cylinder heads and remove the carburetor assembly and joints together. 12 After the carburetors have been removed, stuff clean rags into the joints or intake ports to prevent the entry of dirt or other objects. 13 Inspect the carburetor joints (see illustration). If theyre cracked or brittle, replace them. The O-rings should be replaced whenever the joints are removed (see illustration). Installation 14 Engage the carburetor assembly with the intake joints. Lightly lubricate the ends of the throttle cables (or cable) with multi-purpose grease and attach them to the throttle pulley. Make sure the accelerator cable (and decelerator cable if equipped) are in their proper positions. .• 15 Pull the air cleaner joints down from the air cleaner cavity and fit them over the carburetors. 16 Make sure the carburetor is seated securely in the intake joints and the air cleaner joints are fitted securely over the carburetors, then tighten the clamping band screws. 17 Adjust the throttle grip freeplay (see Chapter 1). 18 The remainder of installation is the reverse of the removal steps. 19 Check and, if necessary, adjust the idle speed and carburetor synchronization (see Chapter 1). 7 Carburetors - disassembly, inspection, cleaning and reassembly Warning: Gasoline (petrol) is extremely flammable, so take extra precautions when you work on any part of the fuel system. Dont smoke or allow open flames or bare light bulbs near the work area, and dont work in a garage where a natural gas-type appliance (such as a water heater or clothes dryer) is present. If you spill any fuel on your skin, rinse it off immediately with soap and water. When you perform any kind of, work on the fuel system, wear safety glasses and have a fire extinguisher suitable for class B type fires (flammable liquids) on hand. Disassembly Refer to illustrations 7.1, 7.2a, 7.2b, 7.2c, 7.3a, 7.3b, 7.4a through 7.4e, 7.5a, 7.5b, 7.5c, 7.5d, 7.6a, 7.6b, 7.7a, 7.7b, 7.8a, 7.8b, 7.8c, 7.8d, 7.9a, 7.9b, 7.10a, 7.10b, 7.11a through 7.11 e, 7.12a, 7.12b, 7.12c, 7.12d, 7.13a, 7.13b, 7.15a, 7.15b, 7.15c, 7.15d, 7.16a, 7.16b. 7.16c, 7.16d, 7.17 and 7.19 1 Remove the carburetors from the machine as described in Section 6. Set the assembly on a clean working surface. Note: Work on one carburetor at a time to avoid getting parts mixed up (see illustration). Most disassembly and cleaning procedures can be accomplished without separating the carburetors. If they mu separated, a surface plate will be needed to join them. 2 Remove the float chamber cover screws (see illustration). Take
3A-8 Chapter 3 Part A Fuel and exhaust systems (XV535 models) 7.2b ... remove the other float chamber cover ... 7.2c ... disconnect the fuel and vent lines and set them aside 7.3a Pull out the float... 7.3b ... and lift out the needle valve 7.4a Unscrew the main Jet.., 7.4b ... and the main nozzle holder ... 7.4c ... remove the O-ring with a pointed tool... 7.4d ... remove the jet block screws ... 7.4e ... then lift out the jet block and remove its gasket off both float chamber covers, the fuel lines and the vent lines (see illustrations). 3 Slide the float off its pivot pin and lift out the needle valve (see illustrations). 4 Unscrew the main jet, the jet block retaining screws and the main nozzle holder, then lift the jet block out (see illustrations). 5 Remove the two rubber plugs from the end of the jet block, then unscrew the pilot jet and main bleed pipe (see illustrations). 6 Remove the front carburetors coasting enricher valve cover, spring and diaphragm (see illustrations).
Chapter 3 Part A Fuel and exhaust systems (XV535 models) 3A-9 7.5a Pull the two rubber plugs out of their passages . 7.5b ... unscrew the pilot jet... 7.5c ... and the main bleed pipe 7.5d Jet block components A Jet block B Pilot jet C Rubber plug D Rubber plug E Main bleed pipe F Main jet G Main nozzle holder 7.6a Remove the screws and lift off the coasting enricher valve cover ... 7.6b ... then lift out the spring and diaphragm
3A-10 Chapter 3 Part A Fuel and exhaust systems (XV535 models) 7.7a Note the locations of the hose clips and remove the cover screws . .. 7.7b ... one of the screws requires a Torx bit 7.8a Lift off the cover ... 7.8b ... and remove the spring 7.8c Carefully separate the diaphragm from the carburetor body without tearing it... 7.8d ... and remove the O-ring 7.9a Remove the O-ring from the main nozzle ... 7.9b ... then push the main nozzle into the throttle bore (arrow) and remove it 7.10a Unscrew the no. 2 pilot air jet from the vacuum chamber ... 7 Remove the vacuum chamber cover screws (see illustrations). One of the screws requires a Torx bit (Yamaha US tool no. YU- 05258/UK part no. 90890-05349). 8 Lift off the vacuum chamber cover and remove the spring (see illustration). Separate the vacuum piston diaphragm from the carburetor body, using care not to tear it, then remove the O-ring from the passage with a pointed tool (see illustrations). 9 Push the main nozzle into the throttle bore, then remove the nozzle and its O-ring (see illustrations). 10 Unscrew the pilot air jets from the vacuum chamber (no. 2) and from the throttle bore (no. 1) (see illustrations). 11 Loosen the two screws that secure the choke link (see illustration). Remove the pivot screw, retaining clip and washer and take off the choke lever (see illustrations).
Chapter 3 Part A Fuel and exhaust systems (XV535 models) 3A-11 7.10b ... and the no. 1 pilot air jet from the throttle bore (arrow) 7.11a Loosen the choke link securing screws (theres one for each carburetor)... 7.11b ... remove the choke lever pivot screw . 7.11c ... its spring and washers 7.11d Remove the clip and washers ... 7.11e ... and take off the choke lever
3A-12 Chapter 3 Part A Fuel and exhaust systems (XV535 models) 7.12a Remove the clip from the end of the choke link with a pointed tool... 7.12b ... remove the spring retainer ... 7.12c ... the spring . 7.12d ... and pull out the choke link 7.13a Pry the washer and bushing loose with a pointed tool... 7.13b ... and remove them from the choke shaft passage 7.15a Detach the upper stay plate ... 7.15b ... and the lower stay plate ... 7.15c ... note carefully how the synchronizing screw fits in the linkage ... 12 Remove the clip, retainer, spring and choke link (see illustrations). 13 Remove the washer and choke link bushing from each carburetor (see illustrations). 14 This completes disassembly necessary to clean and inspect the jets and passages. One of the choke plunger assemblies and one of the coasting enrichers are located between the carburetors. To remove and inspect these, the carburetors must be separated as described in the following steps. 15 Remove two of the screws from the upper stay plate and two from the lower stay plate (see illustrations). Note how the synchro- nizing screw fits in the linkage, then pull the carburetors apart (see illustrations).
Chapter 3 Part A Fuel and exhaust systems (XV535 models) 3A-13 7.15d ... and pull the carburetors apart 7.16a Unscrew the choke plunger ... 7.16b ... and take it out of the housing 7.16c Remove the housing mounting screws ... 7.16d ... and take the housing and gasket off the carburetor body 7.17 Remove two screws and take the throttle pulley assembly off 7.19 Pilot screw components A Pilot screw B Spring C Washer D O-ring 7.20 Remove the O-ring from each float chamber cover with a pointed tool 16 Remove the choke plunger and housing from the carburetor (see illustrations). 17 Remove the throttle pulley assembly (see illustration). 18 Remove the remaining coasting enricher (see illustrations 7.6a and 7.6b). 19 The pilot (idle mixture) screw is located in a passage in the carburetor body. On US models, this screw is hidden behind a plug which will have to be removed if the screw is to be taken out. To do this, drill a hole in the plug, being careful not to drill into the screw, then- pry the plug out or remove it with a small slide hammer. On all models, turn the pilot screw in, counting the number of turns until it bottoms lightly. Record that number for use when installing the screw. Now remove the pilot screw along with its spring, washer and O-ring (see illustration). Inspection Refer to illustrations 7.20, 7.26a, 7.26b, 7.26c and 7.28 20 Remove the O-ring from each float chamber cover (see illustration).
3A-14 Chapter 3 Part A Fuel and exhaust systems (XV535 models) 7.26a Remove the screw from inside the vacuum piston ... 7.26b ... and lift out the jet needle , 7.26c ... together with the spring, washer, clip and O-ring 7.28 Check the coasting enricher solenoid diaphragms for cracks or brittleness 21 Check the operation of the choke plunger. If it doesnt move smoothly, replace it, along with the return spring. Inspect the needle on the end of the choke plunger and replace it if its worn. 22 Check the tapered portion of the pilot screw for wear or damage. Replace the pilot screw if necessary. 23 Check the carburetor body, float chamber cover and vacuum chamber cover for cracks, distorted sealing surfaces and other damage. If any defects are found, replace the faulty component, although replacement of the entire carburetor will probably be necessary (check with your parts supplier for the availability of separate components). 24 Check the diaphragm for splits, holes and general deterioration. Holding it up to a light will help to reveal problems of this nature. 25 Insert the vacuum piston in the carburetor body and see that it moves up-and-down smoothly. Check the surface of the piston for wear. If its worn excessively or doesnt move smoothly in the bore, replace the carburetor. 26 Remove the screw that secures the jet needle in the vacuum piston (see illustration). Remove the jet needle, spring, washer, clip and O-ring (see illustrations). Check the jet needle for straightness by rolling it on a flat surface (such as a piece of glass). Replace it if its bent or if the tip is worn. 27 Operate the throttle shaft, to make sure the throttle butterfly valve opens and closes smoothly. If it doesnt, replace the carburetor. 28 Check the coasting enricher diaphragm for tears or brittleness (see illustration). Replace them if their condition is in doubt. 29 Check the floats for damage. This will usually be apparent by the presence of fuel inside one of the floats. If the floats are damaged, they must be replaced. Check the float needle valve seating face; if a pronounced groove has formed on the taper, replace the needle valve. Also, check that the tip on the opposite end of the needle valve moves freely against spring pressure. Cleaning Caution: Use only a petroleum based solvent for carburetor cleaning. Dont use caustic cleaners. 30 Submerge the metal components in the solvent for approximately thirty minutes (or longer, if the directions recommend it). 31 After the carburetor has soaked long enough for the cleaner to loosen and dissolve most of the varnish and other deposits, use a brush to remove the stubborn deposits. Rinse it again, then dry it with compressed air. Blow out all of the fuel and air passages in the main body. Caution: Never clean the jets or passages with a piece of wire or a drill bit, as they will be enlarged, causing the fuel and air metering rates to be upset. Reassembly Refer to illustrations 7.32a, 7.32b and 7.32c Caution: When installing the jets, be careful not to over-tighten them - theyre made of soft material and can strip or shear easily. Note: When reassembling the carburetors, be sure to use the new O- rings, gaskets and other parts supplied in the rebuild kit. 32 Assembly is the reverse of the disassembly steps, with the following additions. a) When connecting the carburetors to each other, lay them on a surface plate while tightening the stay plate screws to ensure proper alignment. b) When installing the choke plunger, align its screws with the dimples in the shaft (see illustration). c) Align the slot in the main nozzle with the projection inside the jet block. d) Align the projection on the jet needle washer with the hole in the vacuum piston. e) Align the protrusion on the vacuum piston diaphragm with the notch in the carburetor body (see illustration). f) Align the tab on the coasting enricher diaphragm with the slot in the carburetor body (see illustration). g) Install the carburetors (see Section 6) and check the fuel level (see Section 8).
Chapter 3 Part A Fuel and exhaust systems (XV535 models) 3A-15 7.32a Align the choke shaft screws with the dimples in the shaft (arrows) 7.32b Align the protrusion in the diaphragm with the notch in the carburetor body (arrow) 7.32c Align the tab on the coasting enricher diaphragm with the notch in the carburetor body (arrow) 8.3 Connect the tool to one of the drain fittings (arrows) 8.4 Loosen the float chamber drain screw 8.6 Bend the float tang to change fuel level 8 Carburetors - fuel level adjustment Refer to illustrations 8.3, 8.4 and 8.6 Warning: Gasoline (petrol) is extremely flammable, so take extra precautions when you work on any part of the fuel system. Dont smoke or allow open flames or bare light bulbs near the work area, and dont work in a garage where a natural gas-type appliance (such as a water heater or clothes dryer) is present. If you spill any fuel on your skin, rinse it off immediately with soap and water. When you perform any kind of work on the fuel system, wear safety glasses and have a fire extinguisher suitable for class B type fires (flammable liquids) on hand. 1 Support the bike securely so it cant be knocked over during this procedure. 2 Place a floor jack under the bike and position it so the carburetors are vertical. 3 Attach Yamaha service tool no. YM-01312-A (part no. 90890- 01312) to the drain fitting on the bottom of one of the carburetor float chambers (both will be checked) (see illustration). This is a clear plastic tube graduated in millimeters. An alternative is to use a length of clear plastic tubing and an accurate ruler. Hold the graduated tube (or the free end of the clear plastic tube) vertically against the float chamber cover. 4 Unscrew the drain screw at the bottom of the float chamber a couple of turns (see illustration), then start the engine and let it idle - fuel will flow into the tube. Wait for the fuel level, to stabilize, then note how far the fuel level is below the line on the float chamber cover. 5 Measure the distance between the indicator line and the top of the fuel level in the tube or gauge. This distance is the fuel level - write it down on a piece of paper, tighten the drain screw, then move on to the other carburetor and check it the same way. 6 Compare your fuel level readings to the value listed in this Chapters Specifications. If the fuel level in either carburetor is not correct, remove the float chamber cover and bend the tang up or down as necessary (see illustration), then recheck the fuel level. Note: It isnt necessary to remove the carburetors from the motorcycle since the float chamber screws are accessible from the left side, but be sure the fuel valves turned off and the float chambers drained of fuel before doing so.