1985 Yamaha Tri-Moto, Tri-Z 250, YTZ250 Service Manual

Wiring diagrams, specifications, and repair sequences for powersports ignition and fuel systems. Complete transmission maintenance with five-speed gear ratios and transmission oil procedures. PN F3T2547 CDI magneto.

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Document Details

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Document Number / Seller:
24491 / Stephanie Rogers
File Size:
26.17 MB
File Type:
PDF
Language:
English (some of our manuals are multi-language)
Pages:
137
Printable:
Yes
Estimated Download Time:
0.54 Minutes
Delivery Format:
Digital (PDF) - Instant Access
Category:
Three-Wheeler
Brand:
Yamaha
Reviewed and Approved:
Aug 24, 2025
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Models Covered & Key Technical Specifications

Yamaha Tri-Z 250, YTZ250N (38W) — 1985 Diagnostic Comprehensive Manual | Tri-Z 250 Series File.

  • Engineered Current Rating: The engine displacement is standardized to 246 cm³ (15.0 cu in) representing the primary cylinder volume Sequences.
  • Calibrated Climate Specs: For optimal fuel management, 10.0 L (2.6 Imp gal, 2.6 US gal) defines the tank capacity Baseline.
  • Measured Output Performance: Engine idle speed achieves 1500 ± 50 rpm — represents the baseline crankshaft operating Threshold.
  • Standard Net Mass: The motorcycle requires 143 kg (315.3 lb) with oil and full fuel tank carrying configuration Requirements.
  • Prescribed Assembly Torques: Spark plug fastening sets 25 Nm (2.5 m-kg, 18 ft-lb) throughout the complete installation Mapping.
  • Verified Wattage Specs: Headlight illumination reaches 30 W × 2 units per bulb location for forward visibility Configuration.

Professional Workshop Service Manual & Technical Specifications

Essential Troubleshooting Parts Manual: Three-Wheeler Official Yamaha Tri-Moto Tri-Z 250, YTZ250 ATV Service Manual - Comprehensive Maintenance & Diagnostics Factory-Standards

Engineering-Metrics: Yamaha TRI-MOTO, Yamaha Tri-Z 250, Yamaha YTZ250 (1985 models) // Assembly-Group: Liquid-cooled two-stroke single-cylinder engine / Drive train systems Logic // Model-Portfolio: 137-page comprehensive technical documentation.

Assessment-Parameter Rating Calibration-Standards
Engine Documentation Complete specifications Includes displacement, bore/stroke, compression ratio data
Suspension Systems Comprehensive coverage Front fork and rear shock absorber settings documented
Brake System Full technical detail Disc brake pad wear limits and fluid specifications included

The repository is divided into engine service procedures, chassis maintenance routines, electrical troubleshooting protocols, and appendix resources covering five principal chapters: general information and machine identification materials, regular maintenance intervals with lubrication charts, engine repair and carburetor tuning guidance, chassis service for suspension and brake assemblies, and electrical system diagnostics with wiring schematics, providing an extensive reference for workshop technicians and riders.

Integrated Nexus

Suspension service documentation covers the front fork oil level adjustments, spring rate selections for soft and hard applications, and rear shock absorber preload settings with compression and rebound damping controls. The manual details the monocross suspension system equipped with nitrogen gas pressure specifications and handling precautions for safe component service. Fork oil capacity requirements, assembly procedures with special tool specifications, and inspection protocols for inner tubes, seals, and damper components are comprehensively addressed.

Modular Methodology

Disassembly instructions are documented for carburetor tuning components including jet needle positions, main jet selection by size designation, needle jet configurations, and pilot air screw adjustments across throttle ranges. Detailed procedures address float height measurement, reed valve inspection, and fuel system diagnostics. Spark plug specifications with gap measurements and ignition timing calibration using dial gauge tools are included to ensure proper engine function.

Modular Framework

Wear limits are specified for brake pad thickness minimum standards, clutch friction plate measurements, piston ring end gaps, and tire groove depth indicators for safe operation. Cylinder bore measurements, piston clearance tolerances, and connecting rod specifications establish component service criteria. The documentation addresses seal replacement intervals, bearing inspection protocols, and bushing wear assessment across transmission and suspension systems.

Diagnostic Standard

System operation descriptions cover the CDI magneto ignition architecture with pickup coil resistance testing, charging system voltage output at engine speed thresholds, and lighting circuit voltage regulation. Troubleshooting procedures address spark failure diagnosis, compression system evaluation for hard starting conditions, and air-fuel mixture assessment through spark plug color examination. Electrical harness routing and connection integrity checks ensure system reliability.

Technical Logic-Path

The documentation addresses chassis alignment specifications including steering head bearing preload, front fork pinch bolt torque values, and rear axle runout measurement limits. Wheel bearing inspection methods, rim runout tolerance standards, and tire pressure recommendations for cold conditions are detailed. Drive chain tension adjustment procedures with alignment mark references and sprocket tooth inspection criteria support drivetrain maintenance protocols.

The manual documents torque specifications for fasteners across engine, chassis, and suspension assemblies to ensure proper mechanical fastening throughout the machine.

FAQ

Determine the **specific** torque for the primary drive gear nut? keyboard_arrow_down

115 N·m (11.5 m-kg, 85 ft-lb) is required for the M18 x 1.0 primary drive gear nut to ensure proper clutch assembly tension during engine service.

What specifications apply to **designated** safety components like the steering stem nut? keyboard_arrow_down

85 N·m (8.5 m-kg, 61 ft-lb) tightening torque is required for the M22 x 1.0 steering stem nut to maintain proper steering head assembly alignment and prevent looseness during operation.

Check the **critical** lubrication requirements for front fork service? keyboard_arrow_down

334 cm³ (11.8 Imp oz, 11.3 US oz) of Yamaha fork oil 10 wt or equivalent is required per fork leg, with standard oil level set at 151 mm (5.94 in) from the top of the inner tube when fully compressed.

What does the **required** ignition timing setting specification demand? keyboard_arrow_down

1.66 mm ± 0.1 mm (0.07 ± 0.004 in) before top dead center is the required BTDC specification at standard engine speed to achieve optimum ignition spark timing for maximum engine power output.

Reference the **specified** diagnostic procedure for rear shock nitrogen pressure verification (pages 116+)? keyboard_arrow_down

1,177 kPa (12 kg/cm², 113.7 psi) standard nitrogen gas pressure is specified for the rear shock absorber assembly, with acceptable operating range between 784-1,480 kPa (8-15 kg/cm²) as documented in the chassis maintenance specifications section.

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I found this manual to be incredibly detailed and easy to navigate. The support team was very responsive to my queries, providing helpful assistance. Definitely a worthwhile investment!
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This service manual has been a lifesaver for my Yamaha TRI-MOTO. The download process was super smooth, and I received my link almost immediately after purchase. Highly recommend!