Jet needle adjustment, Standard jet needle | Yamaha WR250FM specification

SETTING

T U N

Jet needle adjustment

The jet needle is adjusted by changing it.

Standard jet needle

OBDVS

* OBELP

* Except for USA

The tapered sections of all jet needles have the same starting positions, but the needles are available with different straight-portion diameters.

<Example> OBDVS - 4

Clip position

Diameter a of straight portion

Effects of changing the jet needle (reference)

(Diameter of the straight portion)

Changing the diameter of the straight portion adjusts the air-fuel mixture when the throttle is 1/8 to 1/4 open.

È

1/4

1/2

3/4

R

T

ÈIdle

ÉFully open

É

+10 %

S

–10 %

7 - 7

Image 327

Yamaha WR250FM Jet needle adjustment, Standard jet needle, Obdvs Obelp, Effects of changing the jet needle reference

Contents

WR250FR Page WR250FR Introduction Page Always Maintain Your Machine in Proper Working Order Always Wear Protective Apparel Gasoline can Cause Injury Park the Machine Carefully Turn OFF the EngineProperly Secure the Machine Before Transporting IT Weights of machines without fuel M. Machine Weights Finding the Required Particularly Important Information Manual Format HOW to Read Descriptions GEN Spec Info Insp ENG ADJ Memo Index Chapter Regular Inspection Adjustments AC Magneto SEAT, Fuel TankValves and Valve Springs Right Crankcase Cover Throttle Position Sensor Electrical Components Description Description Info Model Label Machine IdentificationVehicle Identification Number Engine Serial Number Important Information Preparation for Removal and Disassembly Bearings and OIL Seals ALL Replacement PartsLock WASHERS/PLATES and Cotter Pins GASKETS, OIL Seals and O-RINGS Circlips Checking of Connection Special Tools Part number Tool name/How to use Illustration ACC-QUICK-GS-KT Start Switch Main SwitchMain switch indicator light Engine Stop Switch Throttle Grip Clutch LeverShift Pedal Kickstarter Crank HOT Starter Lever Rear Brake PedalFuel Cock Cold Starter Knob Nipple Wrench Light SwitchValve Joint Spark Plug Wrench Fuel AIR Filter Maintenance Starting and BREAK-INStarting a Cold Engine Do not warm up the engine for extended periods of time Starting a Warm Engine Restarting an engine after a fallEngine fails to start PISTON, RING, VALVES, Camshafts and Gears BREAK-IN ProceduresCylinder and Crankshaft About one hour of break-in operation is necessary TORQUE-CHECK Points Cleaning Cleaning and Storage Storage 5UM4 CDN, AUS, NZ, ZA General Specifications FCR-MX37 CDI Engine Maintenance Specifications Head diameter Face width Seat width Margin thickness 1.6 mm Spec USA EUROPE, CDN ZA, AUS, NZ Spec Part to be tightened Thread size ’ty Tightening torque Silencer USA, CDN Europe AUS, NZ, ZA Chassis USA, CDN, ZA EUROPE, AUS, NZ Upper bracket and outer tube Nipple spoke Rear wheel sprocket M4 ⋅ 5UL-00/DENSO Electrical ACM33221 M06/MATSUSHITA Mkg Ftlb 10 mm 12 mm 14 mm 17 mm 19 mm 22 mm 16 mm 130 General Torque SpecificationsDefinition of Units Torque Cable Routing Diagram Spec Spec Spec Spec Spec Spec Spec Spec Insp ADJ Maintenance Intervals Cooling System Maintenance Intervals ADJ Marked For USA General Inspection and Maintenance PRE-OPERATION Inspection and Maintenance Coolant Level Inspection Coolant ReplacementDo not remove the radiator cap when the engine is hot Engine Coolant Replacement Fill Radiator Engine To specified level Radiator CAP Opening Pressure Inspection Radiator CAP Inspection Standard pressure KPa 1.8 kg/cm2, 25.6 psi Clutch AdjustmentRadiator cap opening pressure KPa 1.1 kg/cm2, 15.6 psi Cooling System Inspection Throttle grip free play adjustment steps Throttle Cable AdjustmentClutch lever free play adjustment steps Throttle Cable Adjustment Hot starter lever free play a 3 ~ 6 mm 0.12 ~ 0.24 HOT Starter Lever AdjustmentHot starter lever free play adjustment steps Throttle Lubrication AIR Filter Cleaning AIR Filter Cleaning Insp ADJ Engine OIL Level Inspection Engine OIL Level Inspection Engine OIL Replacement Engine OIL ReplacementAPI Standard Oil filter element cover 10 Nm 1.0 m kg, 7.2 ft lb Replacement steps Install Copper washer 1 New Oil strainer frame OIL Pressure Inspection Pilot Screw Adjustment Valve Clearance Inspection and Adjustment Engine Idling Speed Adjustment Valve Clearance Inspection and Adjustment Pad range Pad Availability Increments 20 mm Mm increments40 mm Example Last digit of pad Rounded value Exhaust Intake Spark Arrester Cleaning For USA CHASSIS/BRAKE System AIR Bleeding ChassisBrake System AIR Bleeding Front Brake Adjustment Front Brake AdjustmentBrake lever position adjustment steps Front Brake PAD Inspection and Replacement Rear Brake Adjustment Front Brake PAD Inspection and Replacement Do not reuse the drained brake fluidBleed screw Nm 0.6 m kg, 4.3 ft lb Brake pad thickness Mm 0.25 in Limit 1.0 mm 0.04 Rear Brake PAD Inspection and ReplacementRear Brake PAD Inspection and Replacement Pad pin plug Nm 0.3 m kg, 2.2 ft lb Pad pin 18 Nm 1.8 m kg, 13 ft lb Brake Fluid Level Inspection Rear Brake PAD Insulator Inspection Drive chain length 10 links Limit 150.1 mm 5.91 Sprockets INSPECTION/DRIVE Chain InspectionSprockets Inspection Drive Chain Inspection Drive Chain Inspection Drive chain slack 40 ~ 50 mm 1.6 ~ 2.0 Drive Chain Slack AdjustmentDrive Chain Slack Adjustment Drive chain slack adjustment steps Front Fork Inspection Front Fork OIL Seal and Dust Seal CleaningAxle nut 125 Nm 12.5 m kg, 90 ft lb Locknut 16 Nm 1.6 m kg, 11 ft lb Front Fork Internal Pressure Relieving Front Fork Rebound Damping Force Adjustment Standard position 9 clicks out Clicks out Front Fork Compression Damping Force Adjustment Rear Shock Absorber Inspection Standard position 14 clicks out Clicks outRear Shock Absorber Inspection Rear Shock Absorber Spring Preload Adjustment Standard position About 7 clicks out About 10 clicks out Standard position About 9 clicks out About 10 clicks out Rear Shock Absorber LOW Compression Damping Force Adjustment Standard position About 1-1/4 turns out Wheel Inspection Tire Pressure CheckStandard tire pressure KPa 1.0 kgf/cm2, 15 psi Spokes Inspection and Tightening Steering nut wrench YU-33975/90890-01403 Steering Head Inspection and AdjustmentSteering Head Inspection Adjustment Steering ring nut adjustment steps Steering nut wrench 38 Nm 3.8 m kg, 27 ft lbAvoid over-tightening Lubrication Lubrication Ignition Timing Check ElectricalSpark Plug Inspection Spark plug gap ~ 0.8 mm 0.028 ~ 0.031 Ignition Timing Check First AID in Case of Bodily Contact External Battery Inspection and ChargingBattery Inspection and Charging Keep Batteries and Electrolyte OUT of Reach of Children Remove Battery band Example Measurement steps Charge Battery Charging method using a variable voltage charger Charging method using a constant voltage charger Recommended lubricant Lithium soap base grease Battery REPLACEMENT/FUSE InspectionBattery Replacement First, connect the positive lead 1, then the negative lead Fuse Inspection Pocket tester YU-3112-C/90890-03112Items Amperage rating ’ty Adjusting the Headlight Beams Adjusting stepsReplacing the Headlight Bulbs SEAT, Fuel Tank and Side Covers Removal SEAT, Fuel Tank and Side Covers Side cover Removal Points Exhaust Pipe Silencer Removal Exhaust Pipe and Silencer Silencer and exhaust pipe Assembly and Installation Silencer and exhaust pipe Radiator Removal Radiator Assembly and Installation Radiator Handling NoteRadiator Install Right radiator Bolt right radiator Carburetor Removal Carburetor Carburetor Disassembly Carburetor Disassembly ENG Carburetor Pilot screw Standard clip position No.4 Groove Needle valveThrottle valve Jet needle Float height Mm 0.31 Measurement and adjustment steps Float heightFloat Air cut valve Assembly and Installation CarburetorStarter plunger Accelerator pump ENG ENG Pilot screw Turns out example 8 turns out ENG Accelerator pump timing adjustment Adjustment steps Carburetor installationThrottle valve height Mm 0.06 Carburetor ENG Carburetor ENG Camshafts Cylinder Head CoverCylinder Head Cover Removal Camshafts Removal Camshafts Camshaft Runout camshaft Less than 0.03 mm 0.0012 Bolt camshaft cap 10 Nm 1.0 m kg, 7.2 ft lb Timing chain tensioner Assembly and Installation CamshaftInstallation steps Decompression system CA U TI O N Camshafts ENG Bolt timing chain tensionerTensioner cap bolt Quick gasket ACC-QUICK-GS-KT Yamaha Bond No Cylinder Head Removal Cylinder Head Cylinder head Assembly and Installation Cylinder head Valves and Valve Springs Removal Valves and Valve Springs Valve spring compressor YM-4019/90890-04019 Valve lifter and valve cotter Valve Margin thickness Intake Mm 0.0315 in Exhaust Mm 0.0276 Runout limit 01 mm 0.0004 Lapping steps Valve spring Yellow Assembly and Installation Valve and valve springCombination of cylinder head and valve lifter Combination Cylinder head mark Valve lifter mark b Color Valve spring compressor YM-4019/90890-04019 Cylinder and Piston Removal Cylinder and Piston Cylinder and piston Piston and piston ringPiston pin puller set YU-1304/90890-01304 Do not use a hammer to drive the piston pin out Piston size P Cylinder bore C 77.00 ~ 77.01 mm 0315 ~ 3.031905 mm 0.002 2nd step End gap Piston ringSide clearance Limit Inside diameter piston 16.002 ~ 16.013 mm 0.6300 ~ 0.6304 Piston pin Cylinder Install Bolt cylinder Clutch Removal Clutch ENG Primary driven gear Clutch housing and bossClutch boss Clutch holding tool YM-91042/90890-04086 Push rod Friction plateClutch plate Warp limit Mm 0.004 Push lever shaft Clutch Assembly and Installation Push lever shaft ENG Install Push rod 2 Ball Push rod 1 OIL Filter ELEMENT, Water Pump and Right Crankcase Cover ENG Impeller shaft Oil sealOil delivery pipe Assembly and Installation Oil seal Impeller shaft gearBearing Right crankcase cover Kickstarter crank Oil filter element Water pump housing Balancer Removal Balancer Balancer shaft Balancer shaft drive gear and balancer shaft driven gear Primary drive gear Nut primary drive gear OIL Pump OIL Pump Removal and DIS Assembly ENG Oil pump Assembly and Installation Oil pump Bolt oil pump assembly L = 30 mm 1.18 Kick Shaft and Shift Shaft Removal Kick Shaft and Shift Shaft ENG Kick shaft and ratchet wheel Kick shaft assemblyShift guide and shift lever assembly Segment Assembly and Installation Shift shaftStopper lever Install Torsion spring Stopper lever Bolt stopper lever Kick shaft assembly Kick idle gear AC Magneto and Stator Removal AC Magneto and Starter Clutch ENG Woodruff key RotorRotor puller YM-04141/90890-04141 AC magneto Assembly and Installation AC magneto and starter clutch Install Holder Bolt Plain washer rotor Nut rotor Bolt engine guard rear Engine Removal Engine Removal ENG Engine removal Drive sprocket Brake pedal Assembly and Installation Engine installation Oil hose and neutral switch Nm 0.4 m · kg, 2.9 ft · lb Crankcase and Crank Shaft Removal Crankcase and Crankshaft ENG Crankcase Bearing Removal Crankcase Bearing Separation steps Crankcase Crankshaft Crankcase separating tool YU-1135-A/90890-01135Timing chain and timing chain guide Dial gauge and stand YU-3097/90890-01252 Standard Limit Do not use a hammer to drive in the crank- shaft Assembly and Installation Crankcase bearing Apply Sealant On the right crankcase Tighten Hose guide Clutch cable holder Bolt crankcase TRANSMISSION, Shift CAM Shift Fork Removal TRANSMISSION, Shift CAM and Shift Fork Gears Transmission Shift fork, shift cam and segment Assembly and Installation Transmission ENG ENG Front Wheel Removal Front Wheel and Rear Wheel ChasFront Wheel and Rear Wheel Front Wheel Rear Wheel Removal Rear Wheel Rear wheel Wheel bearing if necessaryWheel Brake disc Wheel axleWheel axle bending limit 0.5 mm 0.020 Do not attempt to straighten a bent axle Front wheel 105 Nm 10.5 m · kg, 75 ft · lb Tighten Bolt axle holder Install Trip meter cable 50 Nm 5.0 m · kg, 36 ft · lb 125 Nm 12.5 m · kg, 90 ft · lb Front Brake Removal Front Brake and Rear Brake ChasFront Brake and Rear Brake Front Brake Rear Brake Removal Rear Brake Brake Caliper Disassem BLY Brake Caliper Disassembly Brake Master Cylinder Disassembly Brake Master Cylinder Disassembly Brake fluid Brake caliper piston seal kit Brake master cylinderUse only new brake fluid Brake hose Brake caliper Front brake caliper Always use new piston seals and dust seals Rear brake caliper Brake master cylinder kit Front brake master cylinder Rear brake master cylinder Front brake hose Always use new copper washers CAU TI on CAU T ION Install rear brake only Protector Bolt protector Front Fork Chas Front ForkFront Fork Removal Front Fork Disassembly Front Fork Disassembly Front fork cap bolt Damper rod Inner tubeTake care not to scratch the inner tube Oil seal removal steps Inner tube bending limit 0.2 mm 0.008 Base valveFork spring Fork spring free length 460 mm 18.1 in Limit 455 mm 17.9 Assembly and Installation Front fork assembly Front Fork Chas Fork seal driver YM-01442/90890-01442 Front Fork Chas Front Fork Chas Front Fork Chas Front fork top end standard a 5 mm 0.20 10 mm 0.39 Installation Tighten Pinch bolt upper bracket Handlebar Chas HandlebarHandlebar Removal Handlebar Grip Assembly and Installation Handlebar Install Grip cap cover Cover throttle cable cap Hot starter lever holder Bolt hot starter lever holder Handlebar Chas Steering Chas SteeringSteering Removal Steering Chas Steering stem Steering ring nutTake care not to damage the steering shaft thread Ball race Lower bracket Bearing and ball race Install Washer Steering ring nut Install Washer Steering stem nut Install Trip meter Bolt trip meter Swingarm Chas SwingarmSwingarm Removal Swingarm Disassembly Swingarm Disassembly Relay arm Swingarm Bearing and oil seal Connecting rod Installed depth of bearings a 5 mm 0.20 Swingarm Installed depth of bearings a 5 mm 0.20 80 Nm 8.0 m · kg, 58 ft · lb Tighten Nut relay arm Bolt drive chain support cover = 10 mm 0.39 Rear Shock Absorber Chas Rear Shock AbsorberRear Shock Absorber Removal Starting circuit cut-off relay coupler Handling Note Rear shock absorber Install Spring Upper spring guide Lower spring guide Tighten Adjuster Spring length installed a Bolt rear frame lower Rear Shock Absorber Chas Electrical Components and Wiring Diagram Wiring DiagramColor Code Function of Component MAP-CONTROLLED CDI Unit Inspection Steps Ignition System COUPLERS, Leads and Ignition Coil Connection Inspection Engine Stop Switch InspectionIgnition System Elec + Spark GAP Test Main Switch Inspection Battery + lead → Red/Black lead 1 Battery lead → Black leadTester + lead → Red lead Tester lead → Brown lead Ignition Coil Inspection Resistance Position 08 ~ 0.10 Ω at 20 C 68 FResistance Position ~ 6.8 kΩ at Tester + lead → Sky blue lead 1 Tester lead → Ground Neutral Switch InspectionAC Magneto Inspection Resistance Position 248 ~ 372 Ω at 20 C 68 F Starting Circuit CUT-OFF System Operation Electric Starting System Inspection Steps Starter Motor Operation BatteryTo battery Couplers and Leads Connection Inspection Clutch Switch Inspection Starter Relay InspectionPull Free Start Switch Inspection Electric Starting System Elec +Diode Inspection Starter Motor Starter Motor RemovalStarter Motor Disassem BLY Inspection and Repair Min. commutator diameter 16.6 mm 0.65Mica undercut 1.5 mm 0.06 Assembly Be careful not to damage the brush during installationMin. brush length Mm 0.14 New Charging System Resistance Position 288 ~ 0.432 Ω at 20 C 68 F Charging Voltage InspectionTester + lead → Red lead Tester lead → Black lead Voltage Position 14.1 ~ 14.9 V at DCV-20 000 r/min Throttle Position Sensor System Throttle Position Sensor System Elec + Throttle Position Sensor Coil Inspection~ 6 kΩ at Throttle Position Sensor Replacement and Adjustment Coil variable resistanceAt 20 C 68 F DCV Tester + lead → Yellow lead Tester lead → Black leadThrottle position Tester selector 58 ~ 0.78 ~ 6 DCV-20 Throttle Position Sensor Input Voltage Inspection Lighting System Light Switch Inspection OFFRECTIFIER/REGULATOR Inspection Carburetor setting Setting Settings Effects of the setting parts on the throttle valve opening Main systemPilot system Main jet adjustment Standard main jet #185 #172Effects of changing the main jet reference Setting T U N Jet needle groove position adjustment Effects of adjusting the pilot jet reference Effects of changing the jet needle reference Jet needle adjustmentStandard jet needle Obdvs Obelp Standard leak jet #90 Relationship with throttle opening Leak jet adjustment accelerator pump adjustment STD Examples of carburetor setting depending on symptom Standard secondary reduction ratio 52/13 Selection of the secondary reduction ratio Sprocket 5NY-25448-00 9383B-132185GS-25448-50 Sprocket Change in level and characteristics of fork oil Front fork setting Spring preload adjustment Setting of spring after replacement Rate Part NumberSpring Mark Rear suspension setting Choosing set lengthStandard figure 90 ~ 100 mm 3.5 ~ 3.9 Setting of spring after replacement Setting Rear shock absorber setting parts Adjustment bSpring Free Extent Suspension setting One passenger is astride seat Printed on Recycled Paper Shingai Iwata Shizuoka Japan