1992 YAMAHA YZ250 2-STROKE DIRT Bike Factory Service & Work Shop Manual

INTRODUCTION Congratulations on your purchase of a Yamaha YZ series. This model IS the culmination of Yamaha's vast experience in the production of pacesetting racing machines. It represents the highest grade of craftsmanship and reliability that have made Yamaha a leader. This manual explains operation, Inspection, bas- IC maintenance and tuning of your machine If you have any questions about this manual or your machine, please contact your Yamaha dealer. NOTE: ____________________ _ As Improvements are made on this model, some data In this manual may become outdated. If you have any questions, please consult your Yamaha dealer. AWARNING PLEASE READ THIS MANUAL CAREFULLY AND COMPLETELY BEFORE OPERATING THIS MACHINE. DO NOT ATTEMPT TO OPERATE THIS MACHINE UNTIL YOU HAVE ATTAINED A SATISFACTORY KNOWLEDGE OF ITS CONTROLS AND OPERATING FEATURES AND UNTIL YOU HAVE BEEN TRAINED IN SAFE AND PROPER RIDING TECHNIQUES. REGULAR INSPECTIONS AND CAREFUL MAIN· TENANCE, ALONG WITH GOOD RIDING SKILLS, WILL ENSURE THAT YOU SAFELY ENJOY THE CAPABILITIES AND THE RELIA- BILITY OF THIS MACHINE.

IMPORTANT NOTICE THIS MACHINE IS DESIGNED STRICTLY FOR COMPETITION USE, ONLY ON A CLOSED COURSE. It IS Illegal for this machme to be operated on any public street, road, or highway. Off- road use on public lands may also be illegal. Please check local regulations before riding. ASAFETY INFORMATION 1. THIS MACHINE IS TO BE OPERATED BY AN EXPERIENCED RIDER ONLY. Do not attempt to operate this machine at maximum power until you are totally familiar with its charac- teristics. 2. THIS MACHINE IS DESIGNED TO BE RIDDEN BY THE OPERATOR ONLY. Do not carry passengers on this machine. 3. ALWAYS WEAR PROTECTIVE APPA- REL. When operating this machine, always wear an approved helmet with goggles or a face shield. Also wear heavy boots, gloves, and protective clothing. Always wear proper fitting clothing that will not be caught in any of the moving parts or controls of the machine. 4. ALWAYS MAINTAIN YOUR MACHINE IN PROPER WORKING ORDER. For safety and reliability, the machine must be properly maintained. Always perform the pre-operation checks indicated in this manual. Correcting a mechanical problem before you ride may prevent an accident.

5. GASOLINE IS HIGHLY FLAMMABLE. Always turn off the engine while refueling. Take care to not spill any gasoline on the engine or exhaust sys- tem. Never refuel in the vicinty of an open flame, or while smoking. 6. GASOLINE CAN CAUSE INJURY. If you should swallow some gasoline, inhale excess gasoline vapors, or allow any gasoline to get into your eyes, contact a doctor immediately. If any gasoline spills onto your skin or clothing, immediately wash skin areas with soap and water, and change your clothes. 7. ONLY OPERATE THE MACHINE IN AN AREA WITH ADEQUATE VENTI- LATION. Never start the engine or let it run for any length of time in an enclosed area. Exhaust fumes are poisonous. These fumes contain carbon monoxide, which by itself is odorless and color- less Carbon monoxide is a dangerous gas which can cause unconsciousness or can be lethal. 8. PARK THE MACHINE CAREFULLY; TURN OFF THE ENGINE. Always turn off the engine if you are going to leave the machine. Do not park the machine on a slope or soft ground as it may fall over. 9. PROPERLY SECURE THE MACHINE BEFORE TRANSPORTING IT. When transporting the machine in another vehicle, always be sure it is properly secured and in an upright position and that the fuel cock is in the "OFF" position. Otherwise, fuel may leak out of the carburetor or fuel tank.

TO THE NEW OWNER This manual will provide you with a good basIc understanding of features, operation, and basic maintenance and inspection Items of this machine. Please read this manual carefully and completely before operating your new machine. If you have any questions regarding the operation or maintenance of your machine, please consult your Yamaha dealer. NOTE: _________ _ This manual should be considered a permanent part of this machine and should remain With It even If the machine is subsequently sold. NOTICE Some data in this manual may become outdated due to improvements made to this model in the future. If there is any question you have regarding this manual or your machine, please consult your Yamaha dealer . .---F.I.M MACHINE WEIGHTS: Weights of machines without fuel The minimum weights for motocross machines are: for the class 125 cc for the class 250 cc for the class 500 cc minimum 88 kg (194 Ib) .mlnlmum 98 kg (216 Ib) .. minimum 102 kg (225 Ib) In modifYing your machine (e g., for weight reduction), take note of the above Irmits of weight

HOW TO USE THIS MANUAL PARTICULARLY IMPORTANT INFORMATION ~ The Safety Alert Symbol means ATTENTION I BECOME ALERTI YOUR SAFETY IS INVOLVEDI AWARNING Failure to follow WARNING instructions could result In severe injury or death to the machine operator, a bystander, or a person inspecting or repairing the machine CAUTION: A CAUTION indicates speCial precautions that must be taken to aVOid damage to the machine NOTE: A NOTE prOVides key information to make procedures easier or clearer. FINDING THE REQUIRED PAGE This manual consists of seven chapters; "General Information", "SpeCifications", "Regular Inspection and adjustments", "En- gine", "ChaSSIS", "Electrical" and "Tuning" 2 The table of contents IS at the beginning of the manual. Look over the general layout of the book before finding then reqUired chapter and item. Bend the book at ItS edge, as shown, to find the reqUired fore edge symbol mark and go to a page for reqUired item and description.

MANUAL FORMAT All of the procedures in thiS manual are organized in a sequential, step-by-step format The Informa- tion has been compiled to provide the mechanic with an easy to read, handy reference that contains comprehensive explanations of all disassembly, repair, assembly, and Inspection operations In thiS revised format, the condition of a faulty component will precede an arrow symbol and the course of action required will follow the symbol, e g , -Bearings Pitting! Damage ~ Replace. HOW TO READ DESCRIPTIONS 1. An easy-to-see disassembly illustration IS mainly provided for a disassembly job. 2. Numbers are given In the order of a disassembly job in the disassembly illustration. 3. An explanation of jobs and notes IS presented In an easy-to-read way by the use of symbol marks The meanings of the symbol marks are given on the next page. 4. A job instruction chart accompanies the assembly Illustration, providing the order of jobs, names of parts, notes in jobs, etc. 5. In addition to the disassembly illustration, "Points for Removal" IS proVided to supplement in de- tail the explanation which does or cannot necessarily cover the main jobs. 6 Jobs necessary before and after those which are not Included In the dlsassebly Illustration are ex- plained before the same Illustration as related jobs CD (2) Section Order of removal @ Note on removal and reassembly ® Part name ® Q'ty 10 CARBURETOR AND REED VALVE I ENG ,,-I CARBURETOR AND REEO VALVE i-l PREPARATION FOil REMOVAL ~ '<TUlft !oe fuel cock '0 OfF' *D'SCQOCOCI ,'", OOS"'1 co t ",e 0 sd' *~U"o'e 'c 'cc " S'EClFCA"O~S ... AI~ j[ "i .:)S:) .,70 "'-"'0.,,"' oEJ33,13 SU)301' piLOT >H ,eJ .'" pILOT AI" SCR~<'I 1 •• 4 (PA S FlOAT A"" 01 ", ,,", HEGHT OW 058' ~ ® ® ® Remarks Removal pOint Extent of removal Symbol mark Exploded diagram 2 3 4 CARBURETOR AND REED AlVE t ENG ,.1 NOTE ON II MOVAl AND REASSEMBLY &-- rr,,,"O , """"'"'" C p",~ 9 '"" m o C" t1 ,cod." ,O~C ': ~:o: ,~ $," PO",,' ~;:::QP' c~ B C"""oo ''''" ,0 "oe" v, ~< ,,"''"0 , 32_.S'"'~"'::"V"¥" 11 It"".,,,, ---I ® 6 REMOVAL POINTS ..... E----'0 ThroW. v.I •• '" '~,"g 2 'Spnng lttuottlo "Ivel 3 oM","9 ch,moo, ,Op 4 <Th'o"l. cot>'c 5

CD ® II~~~I~~I I SPEC I Pf I ® @ I ~g~I.a1 ENG " @ .. ® ® !CHASI~I ! ELECle! (J) ® ~ ! TUN I ~I ® ~ ® ~ iD ~ (J] I~I @ ~ (i3I ~ @ @ @ 1 1 1 (?) 0 e @ :[]J ® 1- "i' ~ i p. ILLUSTRATED SYMBOLS (Refer to the illustration) Illustrated symbols CD to (j) are designed as thumb tabs to Indicate the chapter's number and content. CD General Information C2l Specifications ~ Regular Inspection and adjustments 4 Engine @ ChassIs ® Electrrcal (J) Tuning Illustrated symbols @ to @ are used to identi- fy the specifications appearrng In the text. ® With engine mounted ® Special tool ® Filling fluid ~ Lubrrcant 1 Tightening @ Specified value, Service Irmlt @i Resistance ml, Voltage (VI, Electrrc current (AI Illustrated symbols ® to @ In the exploded diagram Indicate grade of lubrrcant and location of lubrrcatlon pOint ® Apply gear all ® Apply engine mixing all @ Apply molybdenum disulfide all @ Apply Irghtwelght Irthlum-soap base grease ®I Apply molybdenum disulfide grease @ Apply locking agent (LOCTITE® \

INDEX GENERAL INFORMATION SPECIFICATIONS REGULAR INSPECTION AND ADJUSTMENTS ENGINE CHASSIS ELECTRICAL TUNING

CONTENTS CHAPTER 1 GENERAL INFORMATION DESCRIPTION . 1- 1 MACHINE IDENTIFICATION .... 1-2 VEHICLE IDENTIFICATION NUMBER (For USA, CDN, AUS and NZ) ... ' . 1-2 FRAME SERIAL NUMBER (Except for USA, CDN, AUS and NZ). .. .1-2 ENGINE SERIAL NUMBER 1-2 IMPORTANT INFORMATION 1-3 PREPARATION FOR REMOVAL AND DISASSEMBLY 1-3 ALL REPLACEMENT PARTS 1-4 GASKETS, OIL SEALS AND O-RINGS .... .1-4 LOCK WASHERS/PLATES AND COTTER PINS 1-4 BEARINGS AND OIL SEALS 1-4 CIRCLIPS 1-5 SPECIAL TOOLS 1-5 FOR TUNE UP 1-5 FOR ENGINE SERVICE 1-5 FOR CHASSIS SERVICE 1-7 FOR ELECTRICAL SERVICE 1-8 CONTROL FUNCTIONS 1-9 "ENGINE STOP" BUTTON 1-9 CLUTCH LEVER 1-9 SHIFT PEDAL 1-9 KICK STARTER 1-9 THROTTLE GRIP 1-10 FRONT BRAKE LEVER 1-10 REAR BRAKE PEDAL 1-10 FUEL COCK 1-10 STARTER KNOB (CHOKE) ..... 1-11

You're Reading a Preview

1992 YAMAHA YZ250 2-STROKE DIRT Bike Factory Service & Work Shop Manual

Description

Reviews

Q&A

Recently Viewed