Workshop guide small Lambretta

Workshop · Lambretta 1964–1971

Workshop guide small Lambretta

Maintaining the small Lambrettas: J50, Cento, J125, Starstream and the Luna range.

Which small Lambretta do you have?

J range	J50, Cento (98 cc), J125 and Starstream: pressed-steel frame, upright cylinder.
Luna range	Lui 50, Vega and Cometa 75: open frame with separate leg shields.

Few reliable maintenance values are publicly available for these makes. That is why no valve clearances or settings are given as figures here. Always use the workshop manual for your model for values, or ask the club. A wrong value costs you an engine.

Maintenance schedule in brief

Every drive	oil level, tyre pressures, lights
Every spring	change oil, check spark plugs, check brakes and cables
Per the handbook	valve clearance, contact points or ignition, carburettor(s), gearbox and shaft drive oil
Every two years	replace brake fluid (with hydraulic brakes)

Two-strokes

Always fill up with premix in the ratio from the instruction booklet. Too little oil causes a seizure.
Change the oil in the gearbox; it is separate from the fuel.
Clean the exhaust and exhaust port now and then; two-strokes build up carbon.
Check the compression: low compression points to wear of piston or cylinder.

Known weak points

Watch out for this

Check the frame of a J for cracks. Early frames broke under heavy use; from late 1966 the frame was strengthened.
You need special tools: the engine looks like the large Lambretta’s, but many tools (such as the clutch compressor) do not fit.
Early J50s use 2.75 × 9 inch tyres that are hard to get; later ones 3.00 × 10.
The rear spring and damper unit is rare and expensive. Treat it with care.
The engine mounting transmits vibration; check the rubbers.

SourcesiLambretta: J range (English)Scootering: J-range buyer’s guide (English)

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