MR Bergamo to Britain Moto Rumi Club
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Technical

Technical reference notes, diagrams, and workshop information for Moto Rumi owners.

Technical index

Choose a subject below.

Frame Wheels and brakes Ignition Gearbox Clutch Lights Wiring Crankshaft Pistons and cylinders Chain and sprockets Forks and steering Kick-start Gearchange setup Cables Carburettor specs Oils Tyres

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Frame

The Rumi frame is presented as a cast aluminium structure built from two principal sections.

  • The scooter frame is made up of two parts: the rear section and the front section.
  • Frame parts and mudguard are described as cast aluminium.
  • The finish can be polished to a bright chrome-like look or painted.
Frame
Frame image 1 Frame image 2

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Wheels and brakes

Wheel bearing sizes and brake relining notes are grouped here for quick reference.

  • Recommended front hub bearing size: 15 x 35 x 11, two required.
  • Recommended rear hub bearing size: 20 x 47 x 14, two required.
  • SAFTEK is referenced for brake relining support.
Wheels and brakes
Wheels and brakes image 1 Wheels and brakes image 2

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Ignition

The ignition setup is one of the most detailed technical subjects on the site.

  • Twin contact breakers sit inside the flywheel and should be set to 0.012 inch or 0.30 mm.
  • The flywheel O mark is where the contacts are fully open at TDC; the A mark is where they just begin to open before TDC.
  • To advance timing, rotate the back plate clockwise. To retard timing, rotate it anti-clockwise.
  • Spark plug gap is listed as 20 to 22 thou, around 0.5 mm.
Ignition

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Gearbox

Gearbox details cover both ratios and the bearing and seal references owners need for rebuild work.

  • Post-1956 scooters use a 4-speed gearbox; earlier scooters and some early motorcycles used 3 speeds.
  • The foot change is described as toe and heel, one down and three up.
  • Four gearbox bearings are listed, including 6203 C3/C4 and a 3203 B double-row output bearing.
  • Output shaft seal is listed as 25 x 35 x 8.
Gearbox

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Clutch

The original clutch guidance is specific about oil choice because wet clutch slip is a known issue.

  • The clutch runs in oil and uses three cork plates with three metal plates.
  • Straight classic SAE 30 oil is recommended to prevent clutch slippage.
  • Modern additive-heavy oils are warned against because they can reduce clutch friction.
Clutch

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Lights

Lighting notes cover the original 6V arrangement and common later conversions.

  • Lights are powered by the 6V magneto lighting coil.
  • Early scooters used a swivelling headlight for cornering; later models used a fixed light.
  • Brake lights were not fitted as standard, though they are noted as a legal requirement on British roads.
  • A 12V system conversion is described as readily available.
Lights

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Wiring

The wiring page explains both standard and battery-equipped arrangements.

  • The original circuit diagram did not use a battery.
  • For brighter lights and better starting, the site notes owners may fit either a 6V or 12V battery system.
  • If a battery is used, a DC horn is required; if wired to AC, an AC horn should be used.
  • The CEV DEP switch is identified as the original Rumi switch, with alternative switch options also noted.
  • The page labels both standard non-battery and with-battery wiring diagrams.
  • Lighting and horn switch connections are shown for the original CEV DEP setup.
Wiring
Wiring image 1 Wiring image 2 Wiring image 3

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Crankshaft

Crankshaft specifications are listed mainly as bearing, seal, and needle roller references.

  • Outer crankshaft bearing: 6303 C3 or C4.
  • Inner crankshaft bearing: 6204 C3 or C4.
  • Outer crankshaft and side-plate seals: 17 x 35 x 7, three required.
  • Centre crankshaft seals: 25 x 42 x 10, two required.
  • Needle roller size is given as 9.80 mm long and 3 mm diameter with rounded ends.
Crankshaft

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Pistons and cylinders

This section distinguishes clearly between standard Formichino and Sport components.

  • Formichino scooters are said to use cast iron cylinders.
  • Tipo Sport models originally used chrome-plated aluminium cylinders before some later examples reverted to cast iron.
  • A three-ring piston is listed for the Formichino and a two-ring piston for the Sport.
  • The piston crown is described as having an unusual V deflector, which the site identifies as a distinct Rumi trait.
Pistons and cylinders

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Chain and sprockets

The chain section ties gearing directly to wheel size.

  • 8-inch wheel scooters use a 14-tooth output sprocket.
  • 10-inch wheel scooters use a 13-tooth output sprocket.
  • Chain size is listed as 1/2 x 3/16 or metric 415 with 98 links.
  • The chain and sprockets sit within the aluminium swing arm.
Chain and sprockets

Technical link

Forks and steering

Front suspension and steering data are kept concise but useful.

  • Suspension is by leading link with springs and limited damping.
  • Damping is adjusted by tightening and locking the nuts on the link arm pin.
  • There are 52 ball bearings in the steering column, 26 upper and 26 lower.
  • The steering ball cups use 26 x 4.75 mm balls in each cup.
Forks and steering

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Kick-start

Kick-start advice focuses on the known wear points in the quadrant and ratchet assembly.

  • The kick-start uses a quadrant and ratchet system.
  • Wear typically appears on the ratchet teeth and bronze bush.
  • The page recommends reworking tooth angles and fitting a longer bush to reduce rocking and improve engagement.
Kick-start

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Gearchange setup

The linked subpage contains the most detailed setup procedure and two different methods.

  • One method aligns grind marks on the gears, selector drum, and idler wheel to place the gearbox between second and third gear.
  • The quadrant is then positioned with its central tooth aligned to the idler mark and held by a spring while the side casing is lowered.
  • The alternative method holds the gear lever in fourth gear while fitting the casing and checking quadrant position.
  • The old page stresses keeping the quadrant in position until the casing bolts have been tightened.
  • The 4th gear method text says to place the clutch ball bearing in the centre clutch recess and confirm the clutch plunger is in place.
  • It then tells the owner to rotate the selector drum clockwise to select 4th gear before lowering the side casing.
Gearchange setup image 1 Gearchange setup image 2 Gearchange setup image 3 Gearchange setup image 4

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Cables

Cable dimensions are given specifically for scooter models.

  • The page labels this section for brakes, clutch, and throttle cables.
  • Rear brake cable: inner L 60 cm, diameter 2.5 mm; outer L 22 cm; lever barrel 7 mm x 6.5 mm.
  • Clutch cable: inner L 140 cm, diameter 1.93 mm; outer L 120 cm; lever barrel 8 mm x 8 mm.
  • Front brake cable: inner L 125 cm, diameter 1.93 mm; outer L 110 cm; lever barrel 8 mm x 8 mm.
  • Throttle cable: inner length variable, diameter 1.08 mm; outer variable; lever barrel 5.63 mm x 3.7 mm.
  • The throttle slide dimension is listed as axial 3.2 mm x 3.4 mm.
  • The note says throttle cable length is variable because of differing twist grip arrangements.
Cables

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Carburettor specifications

The second technical page combines carburation settings with quick ignition references.

  • For the Formichino UA15, turning the adjuster screw clockwise richens the mixture and anti-clockwise weakens it.
  • A mark-to-mark flywheel measurement of 30 mm is listed between A and O.
  • Spark plug types shown include NGK B7ES and Champion N4.
  • Crankcase oil capacity is listed as 2.5 pints and standard petrol/oil mix as 20:1, with synthetic guidance also given.
  • The carburettor and ignition panel also lists points gap as 12 thou or 0.32 mm.
  • Spark plug gap is given there as 20 to 22 thou, or roughly 0.5 to 0.56 mm.
  • The table includes models such as Moto Turismo, Moto Sport, Bi-carburatore, Scoiattolo, Scoiattolo Sport, Standard Formichino, Tipo Sport, Bold'Or, GT200, Regolarita, and Sei Giorni.
  • Needle length is shown as 58 mm on the carburettor specifications panel.
Carburettor specifications
Carburettor specifications image 1 Carburettor specifications image 2

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Oils

Oil advice from the linked page is explicit and conservative.

  • The page says straight classic SAE 30 should be used in the gearbox.
  • It warns that synthetic oils were not designed for early vehicles and may damage seals or cause clutch slip.
  • It suggests no more than 2.25 pints of SAE 30 or equivalent in the gearbox.
  • For petrol mix, classic mineral two-stroke oil at 20:1 or 25:1 is suggested, with semi-synthetic around 35:1.
  • The original text also says many riders are happy to use classic 20/50 oil.
  • It warns that synthetic additives may slowly damage crankshaft seals unless modern materials such as Viton are fitted.
  • One advisory mix figure given is about 200 ml per 5 litres for classic mineral oil.
  • For semi-synthetic, the page gives an approximate figure of 145 ml per 5 litres of petrol.
Oils

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Tyres

Tyre sizes and pressures are included on the linked technical page.

  • 8-inch wheel tyre size: 4.00 x 8.
  • 10-inch wheel tyre size: 3.50 x 10.
  • Tyre pressures listed are front 18 psi and rear 22 psi solo.
  • With pillion, the page lists front 22 psi and rear 28 psi.
Tyres