Yamaha Chappy LB2/LB2M 1978 Service Manual (P/N 1F0-28197-80)

This Yamaha factory service manual (P/N 1F0-28197-80) covers maintenance and repair for the 1978 Chappy LB2 and LB2M. Use the specifications for your model code and market, since equipment and service data vary by version.

PDF Viewing and Wiring Diagram Detail

Search, navigation, and diagram detail: The PDF has no text search or embedded bookmarks. Most pages need to be rotated for upright viewing. Zoom in to read small wire codes and switch labels.

The download is one printable 129-page PDF in English, French, and German. It includes 120 pages of workshop content and chapter indexes, one cover, four introductory and index pages, three memo pages, and one blank final page.

Engine Overhaul, Autolube, and Electrical Diagnosis

These selected workshop topics show the scope of the manual. Other procedures include cleaning the fuel petcock filter and servicing the foam air cleaner.

• Engine overhaul: Crankcase separation, crankshaft removal and installation, decarbonizing, piston and cylinder measurement, and bearing and oil seal inspection.
• Clutch and transmission: Centrifugal and hand clutch inspection, primary gear matching, kickstarter service, transmission and sub-transmission assembly, and shifter adjustment.
• Carburetor and Autolube: Carburetor cleaning and inspection, float height adjustment, reed valve checks, oil pump bleeding, minimum stroke adjustment, and delivery testing.
• Chassis service: Brake shoe and drum inspection, front fork disassembly and reassembly, steering head bearing installation, drive chain adjustment, and swingarm play checks.
• Electrical diagnosis: Contact breaker service, ignition timing, coil and condenser tests, silicon rectifier checks, and charging and lighting system measurements.
• Diagrams and fault charts: Market-specific wiring diagrams, model-specific cable routing, test connection illustrations, and troubleshooting charts for starting and running problems.

The manual is suited to mechanics and owners who are comfortable using workshop measuring tools such as dial gauges, micrometers, and electrical testers.

Engine Wear and Clutch Assemblies

The engine chapter shows how to measure cylinder wear and check piston ring end gap and crankshaft deflection. Standard dimensions and wear limits help determine which parts can be reused during an overhaul.

The clutch illustrations identify the LB2M Type A and Type C assemblies and show components such as roller weights and one-way clutch pawls. Primary gear markings guide backlash matching, while the transmission section shows how to check shift forks and cam grooves before installing the shafts.

The identification section explains how Yamaha marked the frame and engine numbers and shows where to find them.

Carburetor and Autolube Service

The specifications distinguish the Mikuni VM10SC and VM14SC, including their jet needle settings. The carburetor chapter covers float condition and inlet needle and seat wear. Reed valve checks cover petal condition, sealing, and stopper shape, which affects engine output and reed life.

The Autolube section shows how to coordinate the throttle and pump cables and set up the dial gauge. It covers low delivery caused by restricted lines, damaged seals, check ball problems, or air leaks, and specifies when to replace the pump assembly.

Forks, Brakes, and Routine Maintenance

The fork section covers inner tube and component inspection and shows where the oil seal lip can be damaged during reassembly. Separate inspection and lubrication charts organize routine service, and the appendix lists tightening torques for engine and chassis fasteners.

Ignition Tests and Market Wiring

The ignition timing procedure uses point checker 90890-03064 and dial gauge set 90890-01173. The tool illustrations show the stand and measuring components. The fault charts direct readers to component tests for hard starting, poor idle, and weak midrange or high-speed performance.

Separate wiring diagrams cover France, Germany, Belgium, Austria, Denmark, and Sweden. Cable routing views distinguish the 1F1, 1F0, 1F2, and 1V8/1V9 layouts, including rear brake cable differences.

A Preview of Carburetor, Coil, and Oil Data

For float height adjustment, the specifications list 22.0 ± 1 mm for the Mikuni VM10SC on 1V8 and 1V9, and 22.5 ± 1 mm for the VM14SC on 1F0 (551), 1F1, and 1F2 (543).

For ignition coil testing at 20°C, primary winding resistance is 1.7 Ω ± 10% for Hitachi and 1.0 Ω ± 10% for Mitsubishi.

For transmission oil service, the manual distinguishes the 700 cc total capacity from the 650 cc oil change quantity.