User manual YAMAHA YP250

[. . . ] Any reprinting or unauthorized use without the written permission of Yamaha Motor Co. , Ltd. is expressly prohibited. EB001000 NOTICE This manual was produced by the Yamaha Motor Company primarily for use by Yamaha dealers and their qualified mechanics. It is not possible to include all the knowledge of a mechanic in one manual, so it is assumed that anyone who uses this book to perform maintenance and repairs on Yamaha scooter has a basic understanding of the mechanical ideas and the procedures of scooter repair. Repairs attempted by anyone without this knowledge are likely to render the scooter unsafe and unfit for use. [. . . ] Calculate: S Piston-to-cylinder clearance Piston-to-cylinder clearance = Cylinder bore ­ Piston skirt diameter Refer to "CYLINDER" section for cylinder bore measurement. Piston pin bore diameter: 17. 004 X 17. 015 mm <Limit: 17. 045 mm> 4. Piston pin outside diameter: 16. 991 X 17. 000 mm <Limit: 16. 975 mm> 5. Clean or replace. 4-23 CYLINDER AND PISTON YP402111 ENG PISTON RINGS INSPECTION 1. NOTE: Eliminate the carbon deposits from the piston ring grooves and rings before measuring the side clearance. Side clearance (piston ring): Top ring: 0. 04 X 0. 08 mm <Limit: 0. 12 mm> 2nd ring: 0. 03 X 0. 07 mm <Limit: 0. 12 mm> 2. Position: S Piston ring (into the cylinder) NOTE: Push the ring with the piston crown so that the ring will be at a right angle to the cylinder bore. a 5. 0 mm 3. Replace. NOTE: You cannot measure the end gap on the expander spacer of the oil ring. If the oil ring rails show excessive gap, replace all three rings. End gap: Top ring: 0. 15 X 0. 30 mm <Limit: 0. 45 mm> 2nd ring: 0. 30 X 0. 45 mm <Limit: 0. 70 mm> Oil ring: 0. 20 X 0. 70 mm 4-24 CYLINDER AND PISTON EB404184 ENG PISTON RINGS, PISTON AND CYLINDER INSTALLATION 1. Install: S Top ring 1 S 2nd ring 2 S Side rails (oil ring) 3 S Expander spacer (oil ring) 4 NOTE: D Make sure to install the piston rings so that the manufactuer's marks or numbers are located on the upper side of the rings. Install: S Piston 1 S Piston pin 2 S Piston pin clip 3 NOTE: D Apply engine oil onto the piston pins. D The "!" mark a on the piston must face the exhaust side of the cylinder. D Before installing the piston pin clip, cover the crankcase opening with a clean rag to prevent the piston pin clip from falling into the crankcase. Install: S Gasket (cylinder) S Dowel pins 4-25 CYLINDER AND PISTON 4. Position: S Piston rings ENG NOTE: Offset the piston ring end gaps as shown. a b c d Top ring end Oil ring end (lower) Oil ring end (upper) 2nd ring end 5. Lubricate: S Piston outer surface S Piston ring S Cylinder inner surface Engine oil 6. Install: S Cylinder NOTE: D Install the cylinder with one hand while compressing the piston rings with the other hand. D Pass the timing chain and timing chain guide (exhaust side) through the timing chain cavity. 4-26 V-BELT, CLUTCH AND SECONDARY/PRIMARY SHEAVE ENG V-BELT, CLUTCH AND SECONDARY/PRIMARY SHEAVE CRANKCASE FILTER COVER AND CRANKCASE COVER (LEFT) 7 Nm (0. 7 mSkg) 10 Nm (1. 0 mSkg) 7 Nm (0. 7 mSkg) Order Job name/Part name Crankcase filter cover and crankcase cover (left)removal Side panel Q'ty Remarks Remove the parts in order. Refer to "COVER AND PANEL" section in CHAPTER 3. 1 2 3 4 5 6 Crankcase filter cover Crankcase filter cover seal Crankcase filter element Crankcase cover protector Crankcase cover (left) Crankcase cover gasket 1 1 1 1 1 1 Reverse the removal procedure for installation. 4-27 V-BELT, CLUTCH AND SECONDARY/PRIMARY SHEAVE V-BELT, CLUTCH AND SECONDARY/PRIMARY SHEAVE ENG *Shell BT grease No. 3 (90890-69927) 60 Nm (6. 0 mSkg) 3 Nm (0. 3 mSkg) 60 Nm (6. 0 mSkg) Order Job name/Part name V-belt, clutch and secondary/ primary sheave removal Nut/Plain washer Primary fixed sheave Nut Clutch housing Clutch assembly V-belt Primary sliding sheave Collar Primary sheave cap Q'ty Remarks Remove the parts in order. 1 2 3 4 5 6 7 8 9 1/1 1 1 1 1 1 1 1 1 Refer to "PRIMARY SHEAVE REMOVAL" section. Refer to "PRIMARY SHEAVE ASSEMBLY" section. 4-28 V-BELT, CLUTCH AND SECONDARY/PRIMARY SHEAVE ENG *Shell BT grease No. 3 (90890-69927) 60 Nm (6. 0 mSkg) 3 Nm (0. 3 mSkg) 60 Nm (6. 0 mSkg) Order 10 11 12 13 14 Cam Weight Slider Spacer Oil seal Job name/Part name Q'ty 1 8 4 4 1 Remarks Refer to "PRIMARY SHEAVE ASSEMBLY" section. Reverse the removal procedure for installation. 4-29 V-BELT, CLUTCH AND SECONDARY/PRIMARY SHEAVE SECONDARY SHEAVE ENG **Apply BEL-RAY assembly lube® 90 Nm (9. 0 mSkg) Order 1 2 3 4 5 6 7 8 9 10 Job name/Part name Secondary sheave disassembly Nut Clutch carrier Clutch shoe spring Compression spring Spring seat Guide pin Secondary sliding sheave O-ring Oil seal Secondary fixed sheave Q'ty 1 1 3 1 1 4 1 2 2 1 Remarks Disassemble the parts in order. [. . . ] CORRECT : OUT OF SPECIFICATION The wiring circuit from main switch to temperature gauge is faulty. Wiring connection S Check the connections of the entire cooling system. CORRECT Replace the temperature gauge. POOR CONNECTION Correct. 8-43 AUTO CHOKE SYSTEM YP****** ELEC AUTO CHOKE SYSTEM CIRCUIT DIAGRAM Main switch Battery Main fuse Thermo switch (auto choke) Auto choke 10 Ignitor unit 18 Engine stop switch 3 4 5 8 9 8-44 AUTO CHOKE SYSTEM YP****** ELEC TROUBLESHOOTING IF THE AUTO CHOKE FAILS TO OPERATE. Engine stop switch NOTE: D Remove the following parts before troubleshooting. [. . . ]