2009 Derbi GPR 125 4-Stroke Workshop Manual

This 2009 Derbi GPR 125 4-stroke workshop manual, produced by Nacional Motor, S.A.U., covers maintenance, engine repair, chassis service, and electrical checks. The publication is marked Rev. 0.

Searchable Text, Bookmarks and Diagram Detail

Search and diagram access: Body text is searchable, and embedded bookmarks link to chapters and service sections. Small wire codes within the wiring diagram are image-based rather than searchable text; they are readable when enlarged.

One printable, 247-page PDF, including the front cover, two contents pages, and the manufacturer’s closing page. The manual is predominantly in English, with occasional Spanish instructions and diagram labels.

Engine Rebuilding, Carburetor Service and Chassis Repairs

The following highlights are a selection of the manual’s contents. Other topics include pre-delivery inspection and headlight-beam adjustment.

• Engine repair: Engine removal, crankcase separation, cylinder-head work, piston inspection, valve adjustment with calibrated shims, and timing-system reassembly.

• Clutch and transmission: Multi-disk clutch inspection, gear and selector checks, shaft installation, and matched-component identification.

• Fuel and emissions systems: Keihin CVK carburetor disassembly and reassembly, float-level checks, vacuum-valve inspection, automatic-choke testing, and secondary-air-system inspection.

• Cooling and lubrication: Thermostat and temperature-sensor testing, ceramic water-pump seal replacement, double-rotor oil-pump inspection, and oil-circuit diagrams.

• Chassis and brakes: Paioli inverted-fork servicing, steering-bearing work, rear-suspension inspection, brake-component checks, and hydraulic brake bleeding.

• Electrical systems: Wiring diagrams, charging and ignition measurements, starter-circuit references, component replacement, and LCD instrument-panel service-indicator resetting.

Written for Derbi dealer and sub-agency workshops, this manual assumes basic mechanical knowledge and familiarity with vehicle repair methods, together with suitable workshop facilities and tools.

Engine Inspection, Timing and Component Matching

The engine chapter goes beyond removal and installation. It covers valve-seat testing and grinding, cylinder and piston inspection, crankshaft measurements, and internal gearbox assembly. Exploded views identify the crankcase, clutch, and gear-selector components alongside their assembly instructions.

Matched components: Gear-set classifications and the crankshaft bearing-selection chart help mechanics identify compatible replacement parts during a rebuild. Cylinder-base gasket selection is tied to a piston-position measurement using tool 864592 and a dial gauge.

Valve timing: Shim-selection tables and camshaft locking-pin references support valve adjustment. The instructions distinguish the early flywheel timing mark from the alternative reference, helping avoid confusion when setting up the engine.

The manual warns that incorrect handling of the timing-chain tensioner’s center bolt can damage the chain. It also identifies incorrect crankshaft rotation direction during timing work as a risk of serious engine damage.

Carburetor, Cooling and Lubrication Work

The carburetor section explains inspection of the needle, diaphragm, float, jets, and automatic choke, with reassembly and mixture-setting information. It distinguishes serviceable components from fixed carburetor-body fittings that must not be dismantled.

Water-pump repair: Step-by-step instructions cover replacement of the metal-bodied seal with its ceramic interior. This work requires a hydraulic press and tool kit 866380; the section identifies seals and gaskets that must be renewed.

Cooling-system diagrams show the carburetor-heating bypass and coolant routing. Separate lubrication diagrams trace oil through the crankcases, filter, cylinder head, and camshaft supports, with pressure-checking information and double-rotor pump inspection data.

Forks, Steering and Hydraulic Brakes

Fork service includes disassembly, seal replacement, inspection, and refilling. The Paioli assembly uses different internals on each side: the left leg contains the spring, while the right leg acts as the hydraulic damper.

Brake coverage includes caliper and master-cylinder checks, disc wear and runout measurements, and step-by-step bleeding procedures. Rear-suspension work covers swingarm inspection and shock-absorber removal and replacement.

Work around lifting equipment and pressurized fluids requires appropriate protective equipment and a securely supported machine.

Electrical Checks and Instrument Functions

The main wiring diagram, switch-continuity tables, and instrument-panel connector assignments support circuit tracing. Charging-system checks distinguish magneto output, regulator output, and current leakage; ignition checks include the pickup and coil.

Starter-system component references explain the neutral, clutch, and side-stand interlocks. LCD display instructions cover service-indicator resetting, units, and instrument functions, while separate sections address battery, fuse, relay, and CDI replacement.

Examples of Compression and Electrical Test Data

For compression testing on a warmed engine with valve clearances checked and the throttle fully open, the manual lists a standard above 15 kg/cm² and a service limit of 13 kg/cm².

The automatic-choke resistance specification is 20 Ω at 24°C. Charging-system data specifies 13–15 V DC at the regulator output at 8,000 rpm.