Yamaha GPX338F & GPX433F Snowmobile Service Manual

Yamaha GPX338F & GPX433F Snowmobile Service Manual This service manual is the workshop repair reference for the 1974 Yamaha GPX338F and GPX433F snowmobiles and their two-stroke, parallel-twin, air-cooled engines, running 66 pages of removal, disassembly, cleaning, inspection, assembly, and adjustment procedures. It's a true service manual — component-level teardown and repair across the engine, power train, chassis, and electrical systems — backed by service data, carburetor settings, and tightening-torque specifications. Originally published by Yamaha and delivered here as an instant PDF download you can read on any device or print for the bench. Configurations covered: GPX338F (338 c.c.) · GPX433F (433 c.c.) — both covered together in this manual. About the Yamaha GPX338F & GPX433F The GPX338F and GPX433F were Yamaha's performance snowmobiles for the 1974 model year — in Yamaha's naming scheme of the era, the "F" suffix denotes 1974, succeeded by the GPX338G and GPX433G in 1975. Both are powered by two-stroke, five-port induction, natural air-cooled, aluminum-cylinder parallel-twin engines. The GPX338F displaces 20.62 cu. in. (338 c.c.) with a 2.362 × 2.346 in. bore and stroke, while the GPX433F displaces 26.42 cu. in. (433 c.c.) with a 2.677 × 2.346 in. bore and stroke. Both share a recoil hand starter, "Autolube" oil injection, flywheel magneto CDI ignition, a V-belt automatic transmission, and disc brakes. The two sleds share a common chassis — a fabricated aluminum and steel frame, molded steel-reinforced rubber drive track, and 12V lighting — differing primarily in engine displacement and carburetion, with the GPX338F running twin Mikuni BN38-34SH diaphragm carburetors and the GPX433F running twin Keihin CDX42-38 units. Because these machines share so much, a single factory service reference covers both, and that combined documentation is exactly what keeps these vintage Yamaha snowmobiles running when parts and manuals get scarce. What This Manual Covers General: Full specifications and service data for both the GPX338F and GPX433F, plus the special tools, gauges, general tools, and standard tools required to service the snowmobile. Engine removal: Step-by-step procedure for demounting the engine from the frame, including exhaust chamber, silencer, throttle and choke wire, and carburetor handling. Starter: Recoil hand starter parts breakdown and removal. Primary sheave: Disassembly, cleaning and inspection, assembly, and adjustment of the primary sheave, with special-tool callouts and V-belt wear limits. C.D.I. magneto: Removal and service of the flywheel magneto CDI ignition. Carburetor: Model-specific disassembly, cleaning and inspection, assembly, installation, and adjustment for both the Mikuni (GPX338F) and Keihin (GPX433F) carburetors, including the accelerator-pump carburetor on the GPX433F. Oil pump & engine: Autolube oil pump service and engine disassembly procedures. Power train: Secondary sheave removal, inspection, assembly, and adjustment; disc brake service; chain housing; front axle; rear axle; and sliding suspension. Steering (ski) and chassis: Frame, engine mount, oil and fuel, ski, steering, control wires, and shroud. Electrical system: Wiring and electrical component service across the CDI ignition and 12V lighting circuits. Tightening torque: Reference torque specifications for fasteners throughout the machine. Why This Manual Matters Component-level repair, not just operation. This is a workshop service manual — it walks through tearing down and rebuilding the primary and secondary sheaves, carburetors, CDI magneto, oil pump, and engine, which is what you need when a repair goes past routine maintenance. Two models in one reference. Both the GPX338F and GPX433F are documented side by side, so the differences in engine, carburetion, jetting, and ignition are spelled out rather than assumed. The reference data the job depends on. Service data, carburetor jet and adjustment settings, spark plug specs, ignition timing, and tightening-torque figures are included, so you can reassemble to spec rather than guess. Two-stroke and clutch-specific procedures. Autolube oil pump stroke settings, V-belt wear limits, and primary/secondary sheave adjustments are all documented — the details generic guides don't carry. Vintage sleds, scarce documentation. Factory service literature for these early Yamaha GPX snowmobiles is increasingly hard to find — this PDF puts the complete manual back in your hands. Manual Code: 878-28197-10